Regarding your second question, I certainly cannot do that subject any justice in a brief reply, and I haven't time for a long one, so I'll simply say this: Inherent in all religious beliefs/faiths (including mine) is the idea that the believer is correct in their beliefs, so obviously that does imply other religious beliefs/faiths are mistaken, either in minor or major respects. That's inescapable, unless you're an all-religions-are-correct New Age type (which I most emphatically am not).

All that said, what I believe versus the way I treat other people are two separate things. The trouble is, too many people throughout history have confused the two.

As for the what-is-God question, here's a verse from the Bible that has never been mistranslated as far as I know: "God is love" (1 John 4 verse 8).