The Naturalist's Sensus Divinitatis

Plantinga asks: What are the odds that, if we are the products of unguided natural selection, our belief-forming mechanisms are reliable? He thinks the odds are quite low and uses this conclusion as part of an argument against atheism.

When asking this question, he asks: would a creature that is the product of unguided natural selection have reliable belief-forming mechanisms?

The answer to this question is 'yes'. We are the products of unguided natural selection. Our beliefs are the product of reliable belief-forming mechanisms. Accordingly, by Lewis' truth conditions for counterfactual conditionals, it is true that were a creature the product of unguided natural selection, it would have reliable belief-forming mechanisms.

BTW: Lewis: "If P were true, Q would be true" is true if P and Q are true.