If you are an atheist, then, by definition, you are a materialist, because you reject and believe only in the god of the material self that has no soul.  This is why all self-help and New Age "religions" are man-made spiritualities and synthetic imitations of Christianity that are "practiced" by atheists, who believe themselves to be spiritual but not in a Christian way.

Out of the Enlightenment was built a man-made morality based on reason, which tried to replace Christian morality.  Kant told us that only through reason can man find truth; Bacon claimed to give us the foundation of truth through the scientific method; Hegel gave us dialectical materialism that Marxism was built on that attempts to predict the historical inevitability of man's perfection through his own efforts; Hume's empiricism that said knowledge and truth can only be determined through the senses; and Dewey told us truth could be found only in what works in the material world that became the basis of pragmatism and utilitarianism.

Atheist Delusions: The Christian Revolution and its Fashionable Enemies, a book written by the brilliant Christian theologian and thinker David Bentley Hart, covers this topic somewhat:

Hart outlines how Christianity transformed the ancient world in ways we may have forgotten: bringing liberation from fatalism, conferring great dignity on human beings, subverting the cruelest aspects of pagan society, and elevating charity above all virtues.  He then argues that what we term the "Age of Reason" was in fact the beginning of the eclipse of reason's authority as a cultural value.

Could it be that reason itself, the basis for secular humanism, is not the real path to truth in the world and is flawed as a worldview and belief system?  Has anyone considered that rationalism, the offspring of Enlightenment-created reason, has a dark shadow called irrationalism that in the past and now in the present is the cause of so many problems?  Reason is simply an amoral tool that can be used for good or for evil.  German concentration camps during World War II were nothing but their idea of a "reasonable" and systematic – i.e., pragmatic, utilitarian – implementation of the Nazis' version of rationalism for the extermination of Jews.

And more from Atheist Delusions:

Modern persons of a secularist bent, who believe that the roots of their solitude for human equality reach down no deeper in the soil of history than the so-called Age of Enlightenment, often tend to imagine that their values are nothing more than the rational impulses of any sane conscience unencumbered by prejudice.  But this is nonsense.  There is no such thing as "enlightened" morality.

From the classic book by Romano Guardini, The End of the Modern World:

Man is not so constructed as to be complete in himself and, in addition, capable of entering into relations with God or not as he sees fit; his very essence consists in his relation to God.  The only kind of man that exists is man-in-relation-to-God; and what he understands by that relationship, how seriously he takes it, and what he does about it are the determining factors of his character.  This is so, and no philosopher, politician, poet or psychologist can change it.

What the secular humanists all have in common is that they entirely neglect the soul and authentic spirituality of man.  So on this Easter weekend, when the atheists of the world just shake their heads in disbelief at the two most important events in human history, the crucifixion and resurrection of Christ, they are revealing themselves to be one-dimensional materialists who have made themselves into arrogant little gods, believing they are the center of the their own self-enclosed universe, where the world revolves around them – despite any pseudo-spirituality they might believe in and practice.  And it is all rooted in the egocentric material self.