mmm … would hate to jump in …
The first question, it appears to me, assumes that a reason for, or reasons for believing in Christianity are identical or equivalent of those for believing in other religions. Do you hold the position that the reasons for believing in Christianity are identical to those for believing in other religions, like Islam or Buddhism?
As for the second question, it appears simple enough for me. I think philosophers have already skewered these depths and there is nothing logically inconsistent with God. Omnipotence is the ability to do all things. God is a maximally great being. Simple, no bugs.
EDIT: I saw in a later comment of yours, you pulled the classic “can God create a rock so large that He can’t lift?” Here, I’d seriously recommend you start reading the works of professional philosophers, an argument akin to this one would never get published in a journal of the religion of philosophy today anymore. The question is fallacious to begin with, since it actually assumes, a priori, that it is indeed possible for a rock to be so big that God can’t lift it. However, such a rock is logically incoherent, since there is no such thing as a certain weight measurement that somehow cannot be ‘lifted’ by an omnipotent being. The question, therefore, is actually logically incoherent itself to begin with, it would be like asking “can God create a square circle?” or “can God toad a blue?” The answer to these questions is “No, God cannot do that, because you’re requiring God do logically incoherent things, which is impossible.” This does not violate omnipotence, as omnipotence is the ability to do anything. But what you just outlined in your question is not a thing at all, since it’s logically incoherent, it’s just a jumble of English words that don’t actually make any sense at all.