Talk to atheists on their own terms

While this article claims to offer a proof of god that the author thinks persuasive, I hate to be the one to show it fails at what it aims at proving.

The argument here is

A being is said to be possible if we can conceive no contradiction in the idea of it, and impossible if we can conceive a contradiction (as we do in the idea of a square triangle, for example).

but this cannot be said to be true for

 an omnipotent, omniscient, and perfectly good God

for this contains contradictions.