Source of Ultimate Authority
For the secular humanist, mankind is the measure of all things. And, for mankind, science is the ultimate authority, including on moral issues. There is no “ultimate authority” in the sense that there is some higher authority. There is only what we can see, feel, taste, touch, sense, test, measure, etc. There is no non-physical realm or authority stemming from such realm. Mankind is the only known intelligent being capable of making rational decisions about anything. And, as such is the only authority in anything, but that authority is not based on mankind’s ontology or by virtue of being human. That authority is merely a product of mankind’s ability to analyze information and apply the scientific method to the data and come to various conclusions. As such, the secular humanist can say that “science” is the ultimate authority. In addition to being secular humanism’s ultimate authority, science is secular humanism’s only source for epistemology.
Understanding of Epistemology
When asked how one can know what is true, the secular humanist must answer, “Science!” This leads to science (whatever that means) is also the answer to the question of what grounds knowledge. For many popular secular humanists, Bill Nye and Neil DeGrasse Tyson come to mind, this is the one-word answer to everything but particularly how we know anything. However, this philosophical position, scientism, is rejected by many philosophically-minded secular humanists, but it is still popular with social media atheists and the so-called “New Atheists.” This position, scientism, fails its own test because the statement “Science is the only source for truth,” is not a statement of science. There is no way to scientifically test that statement. But, to continue summarizing secular humanism one must turn to how that worldview understand human beings.
Ontological View of Human Beings
In many ways humans in secular humanism could be compared to God in the Christian worldview. Humans are the source of ultimate authority, science, morality, and the reason to do anything. The litmus test for moral actions is whether or not it will bring well-being for others, particularly humans. Also, under secular humanism humans are merely the product of time, chance, and natural pressures. There is nothing special or unique about humanity and it will someday be supplanted by a better species. Humans are nothing more than somewhat advanced animals with the curious ability to self-reflect and consider their actions with a wide-ranging view of its effects. Since humans are the sole source of authority in the secular humanist worldview it actually makes sense that humans are the source and authority for all moral issues as well.
Source of Morality
In keeping with humans being the sole authority for morality, Harris, as seen in the subtitle of his book The Moral Landscape makes the case that science can give us morality and value. A position, no doubt that Dennett would support as he attempts to derive meaning from evolution. The position of secular humanism is that one is obligated to treat humans well. In many ways secular humanism is a kinder, gentler version of atheism. A version of atheism that says one must be kind to humanity. Harris’ whole moral edifice is built on this idea that human wellbeing is paramount and that the moral thing is to follow one’s biological directive to increase one’s own wellbeing as well as that of the human race.
In summary, secular humanism is the view that there is nothing but material reality to the universe, that humankind is the ultimate authority, that science is the only source of knowledge, human beings are merely highly evolved animals, and morality is a sort of scientifically derived rules that say to treat humans kindly.
Explains What It Ought to Explain
The first question in evaluating any worldview is whether or not it explains what it ought to explain. Secular humanism as a worldview fails to explain several features of reality that we know and experience all the time. For example, anything non-physical like mental activities, cannot be explained at all through this worldview. Also, as we explore more and more into the quantum realm even physical reality is seeming less and less explicable from a purely physical standpoint. Also, there are numerous features of the physical world that clearly cannot be explained by purely physical responses. For example, the existence of the physical universe itself fails to explain itself. More and more discoveries surrounding Big Bang cosmology are defying scientific explanation. Therefore, secular humanism fails to explain anything with metaphysical concepts at its core. There is no room for the metaphysical in secular humanism.
Internal Logical Consistency
With the abandonment of any semblance of metaphysics there is one major logical inconsistency that is clear, ontology in general fails for secular humanism. Ontology is a metaphysical concept; therefore, it is not acceptable in secular humanist thought. Also, the epistemology of secular humanism, without any ontological grounding, is merely science as the only arbiter of truth, but that view cannot be tested by science itself and indeed is borrowing from the ontological ideas of religion to progress at all. If science is the only way to analyze truth, then the foundation of science is philosophical, not scientific and the system collapses without an internal logical consistency. Though it may be logically inconsistent, the next question must be whether it is it livable or existentially viable.
While at first glance, and by their own insistence, this view is existentially positive in nature, but in reality, they have to steal an important position from the Christian worldview. The secular humanist has to steal the idea that humans are valuable from the Christian worldview. Under secular humanism there is no ultimate reason to treat other humans well. This is merely an assertion that many people have rejected. This completely ad hoc assertion that one must treat other humans well leads to the next criteria in evaluating a worldview.
Radical Ad Hoc Readjustment
One must ask if secular humanism has or needs to offer some radical ad hoc readjustment after new scientific findings have been made. There is at least one point where this view has sought to radically readjust itself. Before Big Bang cosmology was established those who rejected God as creator of the universe could rest comfortably assuming there was no ultimate beginning, which implies a creator. However, since science has fairly firmly concluded that there was an ultimate beginning, scientists have scrambled to find anything that will allow the dismissal of an ultimate beginning (Hawking’s rounded boundary for the universe, multiverse theories, etc.). The multiverse theory is another radical ad hoc readjustment to Big Bang cosmology and the apparent design of the universe. One area where secular humanism claims victory is in simplicity, which is the next and last question in this analysis.
Simpler Explanations Are Better Than Complex Ones
We take this idea for granted and secular humanists definitely tout this as a strength, that simpler explanations are better. Secular humanism claims to have simpler explanations than Christianity in nearly everything because it omits the Creator. However, there are two problems with this. One, just having a simpler explanation is not enough. It has to be a simpler explanation that also sufficiently explains all the facts. Secondly, removing God as an explanation seems like it would simplify things but it does not because it adds needed explanatory factors. Removing a creator means that in order for biological life to be come to exist time, chance, and natural pressures. Those are three (insufficient) explanatory factors, however, with Christianity only one explanatory factor is needed, God.
Summary of Evaluation
In evaluating the worldview of secular humanism, it is clear that it fails every portion of the test. It is not able to explain existence or answer questions about why we are here and what we ought to do now that we are here. It fails to maintain a logical consistency since it has a logically incoherent epistemology and ontology. It is existentially unviable because it has no basis by which one ought to behave well and borrows from other worldviews to build that part of its worldview. It has gone through major turmoil with the discovery of Big Bang cosmology and has sought to redefine that aspect of its views in various ways. And lastly, it is not really simpler or at least not simpler in a satisfactory manner. In many areas it requires outside inputs to move forward and cannot explain anything fully within itself.
Explains What It Ought to Explain
In order to fairly judge between secular humanism and Christianity one must subject both to the same evaluative criteria. So, in asking whether or not Christianity explains what it ought to explain we see that Christianity explains the human condition, sinfulness, and its uniqueness being made in the image of God. It also explains the source of all reality, God, and the source of morality, also God. In addition to explaining the human condition of sinfulness, Christianity gives a method of redemption and an explanation of the end of the problem with God making all things anew without the problem of sin. What else can be added to these questions? It seems as if Christianity certainly has the answers necessary here, but one must also ask if it is consistent.
Internal Logical Consistency
Though many have attempted to point out logical inconsistencies with the Bible and with Christianity in general, it has stood the test of time and analysis. All of the supposed biblical inconsistencies are almost always due to an extremely literalistic reading of the biblical narrative. Also, though some have attempted to show a logical incoherence in the existence of God and evil, these attempts have failed. The same is true for attempts to show an inconsistency in the concept of omnipotence, they all fail. Christianity offers logically consistent responses to those arguments as well. Not only is Christianity logically consistent it is certainly existentially viable.
The Christian life is existentially viable in every way as it is consistently lived out by millions of happy, well-adjusted, thoughtful Christians all around the world in every level of social structure and in every cultural milieu. Not only is it existentially viable, it is existentially preferable. Christianity gives deeper meaning and goal-oriented life to its adherents. It gives a deep and meaningful source for humanity and an ultimate goal of loving God and following God’s guide for proper human living. Christianity is not just logical and preferable, is also is consistent.
Radical Ad Hoc Readjustment
While some have felt the need to radically readjust Christian views (modern, ultra-liberal Christians), there is no need to nor is there any such readjustment in orthodox Christianity.  In fact, the very concept of orthodoxy resists any such readjustment. The goal of many thoughtful theologians is how we can incorporate new information into orthodoxy not radically readjust our views. In many ways consistency is what is needed in this troubled world and Christianity can be that answer, but there is one more question to analyze in Christianity.
Simpler Explanations Are Better Than Complex Ones
Is Christianity simpler? Though this may seem like “cheating” the Christian worldview can actually give the simplest explanation of all, “God did it.” However, clearly that answer can be a discussion-killer and need not be used for everything or indeed anything. In fact, this is a common criticism of Christianity, that it relies solely on a God-of-the-gaps explanation for everything. However, this is unnecessary as God has given us enough information and we can coherently combine that information with natural studies to come to logical and coherent views of virtually every facet of human existence. We might not know how God did it, but we can easily infer that God did it and that is the only explanation that can cover all the facts.
Summary of Evaluation
While secular humanism failed in every aspect of evaluation, Christianity has passed and passed with flying colors. As Christ said that He had come that we “may have life, and have it abundantly.” (Jn 10:10, NASB) As part of that abundant life Christians have explanations for all the important facets of life, logical consistency, existential consistency, stability, and simpler explanations that deal with what they must deal with to be worthwhile explanations. There are, of course, arguments against Christianity and it is to those one must turn next.
One of the most popular and in some ways difficult to answer criticism of Christianity (and theism in general) is the problem of evil. However, as Craig and others have shown Christianity’s answer to the problem of evil is superior in every way to secular humanism and indeed every other worldview. Although secular humanism gives no account for what it means to be evil at all, and secular humanism must rely on moral relativism which is a self-defeating view of morality, Christianity has no such problem. Under secular humanism nothing is actually right or wrong if there is no objective ontology for moral truth. The secular humanist view is that humans are the sole source for what is evil and the sole judge of what is evil, then what is evil today at one point was not evil at all. What is good today may someday become evil. This inconsistency is particularly clear in the moral problem of evil, but with the natural problem of evil is it also true. For the secular humanist, there is no evil in nature. In fact, without death and disease in nature evolutionary progress is impossible. On the other hand, Christianity has a knock-down argument concerning the existence of evil: “1. If God does not exist, objective moral values do not exist. 2. Evil exists. 3. Therefore, objective moral values exist (some things are evil!). 4. Therefore, God exists.” Christianity takes the so-called problem of evil and makes it an argument for God. That is because if God does not exist, then objective morality and evil would not exist. Therefore, there really is no problem of evil for the Christian. At least not philosophically. There is an existential version of the problem of evil. That version is about degrees of evil. The problem there is in subjectivity. The existential version asks why there is so much evil in the world if there is a good God who could stop it. However, this fails because it is impossible to define how much is too much evil. Also, when exploring how God could eradicate evil without causing evil or removing free will there is no good answer. That is just one argument for God, there are others that one can look to that make the existence of God and the truth of Christianity more secure.
Arguments for the Existence of God
First, the cosmological argument (Craig espouses what he calls the Kalam cosmological argument): “1. Whatever begins to exist has a cause. 2. The universe began to exist. 3. Therefore, the universe has a cause.” Next logically follows concerning the universe and how it is arranged. The teleological argument can be phrased: “1. The fine-tuning of the universe is due to either law, chance, or design. 2. It is not due to law or chance. 3. Therefore, it is due to design.” These two arguments taken together do not get to the truth of the Christian worldview. However, the absolutely essential argument for the Resurrection of Christ will put the nail in the doubting coffin. There is not space to go through all the parts of the arguments here but the basics are simple. There are no alternative explanations for the Resurrection. The various alternate explanations have been defeated in various ways and in various locations. There is much more to be said about the arguments for God but those three and the turned-on-its-head argument from evil are more than enough to establish the reasonableness of the Christian worldview.
Defense of Objective Truth and Moral Values
Before concluding, a short word should be said about truth with regards to the Christian worldview. Objective truth and moral values can only be found in theistic worldviews and Christianity gives the most coherent version of this. In dualistic worldviews the idea fails because they allow a space for an equivalently-powered being to contradict the “good” version of God in every way. If there are two equally-powered beings, one good and one bad, one could never know if the revelation one is receiving is from the good version of god or the bad. However, Christianity offers a consistent position that God in his ultimate goodness and authority is the sole ontological source for objective truth and moral truths.
 Douglas R. Groothuis, Christian Apologetics: A Comprehensive Case for Biblical Faith (Downers Grove, IL: IVP Academic, 2011), 75.
 Ibid., 53-60.
 "Definition of Humanism," American Humanist Association, accessed December 14, 2018, https://americanhumanist.org/what-is-humanism/definition-of-humanism/.
 Marc Kreidler, "What Is Secular Humanism?" Ingersoll Biography - Council for Secular Humanism, August 16, 2018, accessed December 14, 2018, https://secularhumanism.org/what-is-secular-humanism/.
 Stephen Hawking and Leonard Mlodinow, The Grand Design (Place of Publication Not Identified: Transworld Digital, 2015).
 Agarthas888, Cosmos 1 - "The Shores of the Cosmic Ocean,” December 18, 2017, accessed December 14, 2018, https://www.youtube.com/watch?v=gfCc7ZJjHiM.
 Sam Harris, The Moral Landscape: How Science Can Determine Human Values (London: Black Swan, 2012), 2.
 Helen Longino, "The Social Dimensions of Scientific Knowledge," Stanford Encyclopedia of Philosophy, April 12, 2002, accessed December 14, 2018, https://plato.stanford.edu/entries/scientific-knowledge-social/.
 James E. Taylor, "The New Atheists," Internet Encyclopedia of Philosophy, accessed December 14, 2018, https://www.iep.utm.edu/n-atheis/. The section of this article entitled “Works About the New Atheism” has a high quality selection of apologetic responses to New Atheists in particular and secular humanism in general.
 An interesting side note is that, as Bush states, in the secular world humans are losing their humanness.
 L. Russ Bush, The Advancement: Keeping the Faith in an Evolutionary Age (Nashville, TN: Broadman & Holman Publishers, 2003), 33.
 Harris, The Moral Landscape 2.
 Daniel C. Dennett, Darwin's Dangerous Idea: Evolution and the Meaning of Life (New York, NY: Simon & Schuster 1996).
 Harris, The Moral Landscape 1.
 Also, in many ways these cannot be studied by science, which is secular humanism’s sole arbiter of truth.
 Bush, The Advancement 54.
 Stephen J. Williams, What Your Atheist Professor Doesn't Know (But Should). (CreateSpace Independent Publishing Platform, 2013), 32.
 Frank Turek, Stealing from God: Why Atheists Need God to Make Their Case (Colorado Springs, CO: NavPress, 2015).
 Ibid., 92.
 S.W Hawking et al., Brief Answers to the Big Questions (London: John Murray, 2018), 47.
 William Lane Craig, On Guard Defending Your Faith with Reason and Precision (Colorado Springs, Co.: Cook, 2010), Foreword and elsewhere.
 John C. Lennox, Seven Days That Divide the World: The Beginning According to Genesis and Science (Grand Rapids, MI: Zondervan, 2011), 15. This first chapter of Lennox’s book draws an interesting parallel between the Copernican revolution of the moving earth and possible readings/understandings of the “days” of creation in Genesis.
 Bush, The Advancement 55.
 All Scripture references will be in New American Standard unless otherwise noted.
 William Lane Craig, On Guard Chapter 7.
 William Lane Craig, On Guard Chapter 4.
 Stephen J. Williams, What Your Atheist Professor 123. This text also has the most impressive listing of delicately balanced constants of the universe for life to exist.
 Douglas R. Groothuis, Christian Apologetics 529.
 Lee Strobel and Jane Vogel, The Case for Christ: A Journalists Personal Investigation of the Evidence for Jesus (Grand Rapids, MI: Zondervan, 2017).