The fool hath said in his heart,There is no God. (Psalm 14:1)
In Stephen Charnock's classic work, The Existence and Attributes of God (published 1682), he includes a section entitled "Practical Atheism." While reading this recently, I was struck by one sentence in particular. Charnock writes, “Those, therefore, are more deservedly termed atheists, who acknowledge a God and walk as if there were none, than those (if there can be any such) that deny a God, and walk as if there were one” (Complete Works of Stephen Charnock, Vol. 1 [Edinburgh: James Nichol, 1864], p. 186).
In other words, if we call ourselves Christians and yet live as if there is no God, the term "atheist" applies to us more properly than it does to someone who verbally denies the existence of God and yet lives as if God does exist. Charnock appears to wonder whether the second type of person could exist, but he certainly believes the first type exists. Is he correct? Are there people who profess to be Christian but who live as if God does not exist?
I believe Charnock is correct in believing that such persons exist, and I also believe he is correct in saying that such people are properly termed "atheists." Why? Because as Charnock explains, "The testimony of works is louder and clearer than that of words, and the frame of men's hearts must be measured rather by what they do than by what they say." He explains further that "Men's practices are the best indexes of their principles" (p. 185). In short, what people do reveals what they really believe more than what they say.
I would take Charnock's point one step further and suggest that what is going on in such cases is perhaps worse than atheism. One could make the case that is better to deny the existence of God than to profess belief in God and then live in a way that treats God as if He is irrelevant. This is not merely practical, as opposed to verbal, atheism. It is practical blasphemy. To say there is no God is bad enough, but is it not worse to say there is a God and then proceed to ignore Him? I think it is also arguable that "Christian atheists" do more harm to the Church and to the name of Christ than all the professing atheists put together.
So, to what degree is a person a practical atheist? I think the answer is fairly straightforward and it can be answered by asking another question: To what degree would my daily life change if I became a professing atheist? If it wouldn't change much, I'm already there in practice. If I say I believe in God and yet regularly neglect prayer, reading of God's Word, and worship of God, while also unrepentantly practicing the works of the flesh, I am, in Charnock's words, "deservedly termed" an atheist.
We need to respond to professing atheists like Richard Dawkins, but it is much harder to do so when large numbers of professing Christians are living their daily lives as if they believe Dawkins is right.