The early Christians were thought of as atheists by the Graeco-Romans because they rejected the pantheon of the Roman gods; at least, so the story goes. As somewhat of an inversion of that, many of the Post Reformed Orthodox theologians of 16th and 17th century Western Europe believed that anyone who rejected the true and living God revealed and disclosed in Holy Scripture, and in the living Son, Jesus Christ was to be considered an atheist. Personally, as someone who thinks After Barth, I think anyone who rejects the God solely and principially revealed in Jesus Christ is worshipping, as Barth might say, a No-God; in other words, I believe worshipping a concept of God not explicitly based upon God’s Self-revelation in Jesus Christ makes one an atheist (so this would be concordant with the sentiment of the Post Reformed Orthodox). And beyond all this, to invert maybe even the Post Reformed Orthodox, although not de jure, I would have to consider myself an “atheist” when and if someone says they worship a concept of God and godness that is based upon human discovery, philosophical discurvity and projection in regard to the god they worship; even if that God is baptized in the name of Jesus. In other words, I would consider myself an atheist when and if even Christians, whoever they might be, base their conception of God upon the god of the philosophers; a concept of God not based purely on the Self-revelation of God in Jesus Christ (cf. John 1.18).
Getting back to the Post Reformed Orthodox, though; they had a classification of certain types of “atheists,” and one that I find interesting. There is stuff presented in their approach, respectively, that I find constructively helpful towards thinking about this topic with particular reference to the role that “sin” and hamartiology play relative to people’s perceptions of “God.” There are things in the Post Reformed Orthodox’s thinking that I find pretty attractive towards thinking about what atheism might entail, it is just that I don’t really think the Post Reformed Orthodox went far enough; I think they end up relying too much on a philosophical conception of godness in order to conceive of God—particularly when we start thinking about God’s ousia ‘being’ or essendi ‘essence’. Richard Muller offers a helpful detailing of how all of this looked in the development of Post Reformed Orthodoxy; here we pick up Muller as he has just been discussing the role that “proofs” for God’s existence have or have not played in some of the Reformed Orthodox’s thinking. Muller writes:
Although the proofs are posed “against the atheists,” the Reformed orthodox frequently argue that there are no “atheists properly so called,” or, at least, very few. The Reformed orthodox writers typically understood “atheist” in a very broad sense, designed to include all who denied the true God. “There are many kinds of Atheists,” wrote Bucanus, for some entirely deny the existence of God, others worship “feigned gods,” and still others acknowledge the “true God,” but not “as he is,” rather, “as they fancie him to be.” Given this broad sense of the term, the Reformed tend also to direct their arguments against the majority of atheists, namely, against those who do not deny God absolutely, but whose understandings of God are in need of major revision. The homiletical and hortatory dimensions of the Reformed proofs is particularly clear in Charnock’s initial identifications of atheists and atheism. The problem of atheism is not primarily philosophical but hamartiological: “though some few may choke in their hearts the sentiments of God and his providence, and positively deny them, yet there is something of a secret atheism in all, which is the foundation of the evil practices in their lives, not an utter disowning of the being of a God, but a denial or doubting of some of the rights of his nature.”
Whereas, then, there are either no or virtually no “speculative atheists,” those who directly and expressly deny the existence of any superior Being and have absolutely no “sense and belief of deity,” there are many people who have inward doubts concerning the identity of God or may deny to God such attributes or qualities — as providence or justice — that are necessary to any being rightly called God. In addition, they recognize the existence of “practical atheists.” Thus the text of the Psalm (14:1), “The fool hath said in his heart, there is no God,” is not a philosophical text but a “description of man’s corruption.” The point resonates strongly with Calvin’s exegesis of the text. Charnock continues:
Practical atheism is natural to man in his corrupt state. It is against nature as constituted by God, but natural, as nature is depraved by man: the absolute disowning of the being of a God is not natural to man, but the contrary is natural; but an inconsideration of God, or misrepresentation of his nature, is natural to man as corrupt. A secret atheism, or a partial atheism, is the spring of all the wicked practices of the world.
Charnock points out that the “fool” speaks in his “heart,” not in his “head”:
Men may have atheistical hearts without atheistical heads. Their reasons may defend the notion of a Deity, while their hearts are empty of affection to the Deity.
They have “unworthy imaginations” concerning God, engage in “debasing the Divine nature” through idolatry, and exalt human nature unduly. If we are the question of who these practical atheists are, the probable answer is the “cultured despisers of religion” in Charnock’s day, many of whom fit the description of Viret’s “Deists.”
In sentiment there is much to be commended here, in my mind. The issue always, in my view, comes down to an issue of the heart. People have been so polluted by sin noetically that left to themselves and their own sensuous desires they will always and only fashion God in their own image (e.g. Feuerbach comes to mind). People’s wills are in such bondage (i.e. Luther), they are so overcome with other affections (other than affection for God) that all they will “freely” choose is themselves; as such the only God they can discover based upon this weeded ground is one that they manufacture themselves (i.e. think of Calvin’s ‘idol factory’ or simply of the idolatry referred to over and over again in the Old Testament with reference to the nations, but also of course with reference to God’s own covenant people, the nation of Israel).
I think this sentiment in the Post Reformed Orthodox is all well and good, but I just don’t think it goes far enough. Although we need to be sensitive to what they had available to them in their own period of theological and ecclesiastical history, my contention is that they rely much too much on conceptions of God that are correlatively based on the god of the philosophers (like Plato and Aristotle). In other words I don’t think they were radical enough in regard to their doctrine of God; as such the concept of God they offer, often, is too laden down with philosophical accretions that actually emphasize things about God’s Self-presentation that end up distorting who God actually is relative to his Self-revelation in Jesus Christ (which gets fleshed out say in a system like Federal theology and the attending forensic emphases that come along with that). Contrariwise, Thomas Torrance, as he describes Barth’s Christ concentrated approach to theology writes this:
Because Jesus Christ is the Way, as well as the Truth and the Life, theological thought is limited and bounded and directed by this historical reality in whom we meet the Truth of God. That prohibits theological thought from wandering at will across open country, from straying over history in general or from occupying itself with some other history, rather than this concrete history in the centre of all history. Thus theological thought is distinguished from every empty conceptual thought, from every science of pure possibility, and from every kind of merely formal thinking, by being mastered and determined by the special history of Jesus Christ.
The Post Reformed Orthodox need help relative to their doctrine of God. They were heading in the right direction, in principle, but they hadn’t developed enough to the point where they could write something like TF Torrance does here.
I’m leaving many loose ends in this post, but I will have to say I agree with the sentiment of the Post Reformed Orthodox in regard to how they thought of atheism; particularly as they focus in on the impact that sin has on that. But in the end, here in the 21st century, with further theological developments that we can now benefit from (as illustrated by Barth and Torrance), I think the orthodox need to be radicalized. Insofar as they aren’t I would have to claim an “atheist” status in regard to the God they offer up when and if they present us with a God based upon an under-evangelized metaphysic and conception of God resulting in emphases that distort who God has revealed himself to be in his Self-revelation and exegesis in Jesus Christ.
It is ironic, I think, many Christians end up becoming “atheists,” but they aren’t really even rejecting an actual conception of God who is based purely upon his Self-revelation in Christ. Instead they are rightfully rejecting a conception of God who is based too much on a philosophical conception and thus human projection of God wherein the type of spirituality on offer is one that is driven by a performance based quid quo pro type of spirituality; of the type that no thinking and self-reflective person can actually bear up under for too long (just ask Martin Luther about that!).
 Richard A. Muller, Post-Reformation Reformed Dogmatics: The Divine Essence and Attributes, Volume Three (Grand Rapids, Michigan: Baker Academic, 2003), 179-80.
 Thomas F. Torrance, Karl Barth: An Introduction to His Early Theology 1910-1931, 196.