A-theists operate in various categories. There are, at least, A-Theists who simply do not feel inclined to believe in an omnipotent, omniscient, all-good personal God. Often, these formalized A-theists offer their feelings for facts. That is, they argue they are not poorer in any way because they insist that nothing is sacred. They do not usually spend a great deal of time or energy in the proofs portion of research into the divine. What is unverifiable by ordinary means (though theists insist the presence of God is verifiable by acceptable means, sans prejudice) is simply of no interest.
That is to say, many modern A-theists pontificate on matters they have not considered deeply, nor trained to consider, not found to fit their accepted faith system. Purely on the basis of personal desire the bulk of modern A-theism does away with God, so murdering morality and ethics with God.
Then, there is a portion of modern A-theism that is actually Anti-theism. There are two branches, it seems to me, of Anti-Theists.
There are Anti-Theists who venally, irrationally opposed to any Prime Authority. We do not overstep when we look askance at these persons as if they are less than serious. Anti-theists who simply hate the idea of Authority or Accountability can be distinguished from other Anti-theists by the flimsy construct of their arguments. In fact, the radical, hateful Anti-theist seldom has much to say about God, philosophically or theologically. He will mostly point out the failure of religious persons to assimilate the merciful, compassionate conversation of God with Man. He can never see beyond the closest failed Theist.
I will dispense with the usual acknowledgements about the moral lapses of Theists. Morality is an outgrowth of Religious Theism but morality is neither the Source of Religion nor its end. This is particularly true in Christianity wherein Jesus, the Exemplar, repeatedly champions persons remarkably ostracized by their culture on moral grounds.
Simply put, the Anti-Theistic argument against God (actually centered on real or imagined moral lapses of Theists) flounders at the moment one actually finds even one Transformed Theist. A life changed from empty to admirable is the end of the Anti-Theistic screed applied to fallible God followers.
Then, there are the Anti-Theists who wish to have Religious Theism replaced with non-Religious Theism. This is the Anti-Christ as the Instead of-Christ, not actively against in a nihilistic sense, but, instead, with intent to replace a Divine, Spiritual Theos with Some Other Theos.
For American secularists, for instance, the Instead of God has included Revolution, Abolition, Education and Science. Historically, the first two were, Revolution and Abolition, were couched in theological terms. Hymns of revolution and Civil War still echo down through the centuries.
Revolution includes the principles of Liberty, Equality and Fraternity. American society can still be regarded as a revolutionary society. Our history, our culture, our failures, our triumphs, all co-exist in the continuing American struggle to extend its revolutionary promise to all persons within its sphere. This is more difficult than anywhere else in the world because our civil liberties and living standards render us less and less homogeneous.
Abolition is antebellum but did not occur with the Emancipation Proclamation or Lee's surrender. Jackie Robinson has as much to do with Abolition as Abraham Lincoln. Abolition includes Civil Rights, voting laws, poll taxes, Affirmative Action and military service. The language of Abolition is religious, appealing to God's authority and power even in its Enlightenment pronouncements.
The latter explanations for an Instead of God Theism replace God with Education or Science. The advantages of both the terms, Education and Science, are many.
No one can actually argue against Education. Everyone wants a good education. Those who get a good education and many who do not still demand a good education for succeeding generations. What is left undefined is just what is a good education.
I posit this thought; a good education enables a person to think appropriately in real terms. Education, then, cannot be values-absent or even values-neutral.
There are growing concerns about "Science." Recent revelations of inaccurate data presentations in climate change, for instance, make people question the impartiality of the hard Science presenters. This should not startle anyone. Scientists are human, with all the attendant frailties. Fallen scientists, like fallen preachers of other doctrines, are only proof that humans are human.
The real problem for all Mankind comes when Education becomes God or when Science announces its own deification. The "Scientist" cannot have it both ways. He is either an impartial, disinterested specialist capable to gather data or he is a fiery advocate able to provoke on any and all subjects. If he is an Advocate/Evangelist, he enters the realm of rhetoric/logic and philosophy. He cannot order Aristotle around as he can his lab assistants.
Science cannot demand a place on the Throne when it cannot keep its discoveries in appropriate reality to comfort and heal the world. Successful grant applications are not Holy Writ.
Instead of God-Theists search in vain for a life purpose after the End of God. Education disappoints and Science puffs itself up over all aspects of human life, not just Religion. Knowledge, rich or poor, usually arrogates its possessor. Is this why the Apostle Paul told Christians to "…work out their own salvation with fear and trembling…?"
Please note the Instead of Theists do not argue they are right or wrong. They cannot make such an argument for they must first banish simple morality to have a place at all. When one examines the place they make, it is one based on limited human insight and lavish human emotion. What the Instead of Theist thinks or feels or is regarded as acceptable for a "thinking person" becomes fiat law.
Really, is Modern, Secular A-Theism, in any of its incarnations, any kind of improvement over ancient Theism? I do not argue the modern A-Theist in any of his forms is the same as Religion. He is certainly not the same as Christ. In fact, at his most noble, the modern, secular A-Theist is much less than the Christ, upon whom he depends for his freedom, for provision, for discovery in the complexity of Creation and for any meager moral authority he may allow. The A-theist, then, is an ignoble ingrate, who revels in a free society but would not extend that freedom to the masses.
Opinions expressed here are mine alone.