Most people are bothered by those Scripture passages which they cannot understand. But for me, the passages in Scripture which trouble me most are those which I do understand.” –Mark Twain
I've seen the above quote bandied about often, generally by Christians for various effects. In my searching, I see that it is attributed to Twain but can never find a source. The most likely candidates seem to be "Letters from the Earth" or "Mark Twain's Notebook" but I cannot find any evidence that he actually stated such a thing.