The presumption of atheism
Here is J.P. Moreland and William Lane Craig's take on the presumption of atheism. This excerpt is taken directly from their outstanding book, Philosophical Foundations for a Christian Worldview:
“This is the claim that in the absence of evidence of God, we should presume that God does not exist. Atheism is a sort of default position, and the theist bears the weight of burden of proof with regard to his belief that God exists.
The assertion “God does not exist” is just as much a claim to knowledge as the assertion “God exists” and therefore the former requires justification just as the latter does. It is the agnostic who makes no knowledge claim at all with respect to God’s existence, confessing that he does not know whether God exists or does not exist, and so who requires no justification.
But its protagonists are using it in a nonstandard way, synonymous with nontheist, which would encompass agnostics and traditional atheists.
Flew confesses: “the word “atheist” has in the present context (presumption of atheism position) to be construed in an unusual way. Nowadays, it is normally taken to mean someone who explicitly denies the existence … of God … But here it has to be understood not positively but negatively, with the originally Greek prefix “a-“ being read in this same way in “atheist” as it customarily is in … words as “amoral” … In this interpretation an atheist becomes not someone who positively asserts the non-existence of God, but someone who is simply not a theist.”
Such a redefinition of the word atheist trivialized the claim of the presumption of atheism. For in this definition, atheism ceases to be a view, and even babies, who hold no views at all on the matter, count as atheists. One would still require justification in order to know either that God exists or that he does not exist. Absence of evidence is not evidence of absence.
The debate among contemporary philosophers has moved beyond the facile presumption of atheism to the discussion of the so-called hiddenness of God – discussion of the probability or expectation that God if he existed, would leave more evidence of his existence than what we have.
Atheists argue that God, if he existed, would have prevented the world’s unbelief by making his existence starkly apparent (say, by inscribing the label “made by God” on every atom). But why would God want to do such a thing?
On the Christian view it is a matter of relative indifference to God whether people believe that he exists or not. He is interested in building a love relationship with us, not just getting us to believe that he exists. Even demons believe and tremble, for they have no saving relationship with him (James 2:19).
To believe in God, we must believe that God exists. But there is no reason at all to think that if God were to make his existence more manifest, more people would come into a saving relationship with him. Mere showmanship will not bring about a change of heart (Luke 16:30-31).
Interestingly enough, as the Bible describes the history of God’s dealing with mankind, there has been a progressive interiorization of this interaction with an increasing emphasis on the Spirit’s witness to our inner selves (Romans 8:16-17).
In the Old Testament God is described as revealing himself to his people in manifest wonders: plagues in Egypt, pillar of fire and smoke, parting of the Red Sea. But did such wonders produce lasting heart-change in the people? No. Israel fell into apostasy with tiresome repetitiveness. Therefore we have no way of knowing that in a world of free creatures in which God’s existence is as obvious as the nose on your face that more people would come to love him and know his salvation in the actual world.”