Theists are often challenged to provide a sufficient reason to believe in God. Isn't it poetic, then, that when theists cite the Principle of Sufficient Reason (PSR) in support of God's existence, that many atheists object to the PSR? To state the contingency argument yet again:
1. Everything that exists has an explantation of its existence, either in the necessity of its own nature or in an external cause. (Premise)
2. If the universe has an explanation of its existence, that explanation is God. (Premise)
3. The universe exists. (Premise)
4. Hence, the universe has an explanation of its existence. (From 1 and 3)
5. Therefore, the universe's explanation of its existence is God. (From 2 and 4)
The only way to avoid this conclusion is to say that the universe exists by a necessity of its own nature, which very few atheistic philosophers contend, or to deny the PSR, which is premise (1). Yet, if (1) is rejected, why is the theist required to give an explanation of his or her belief in God? It seems to me that unless that atheist presupposes the PSR, then the theist doesn't have to justify his or her belief.