The Bible and religious tradition imply that 1. It is wrong to worship anything other than God, and 2. There is no good excuse for worshipping anything other than God. One question (1) raises is, wrong for whom? Jews and Christians, certainly. I suggest that there is no clear case that idolatry is a sin for Gentile pagans in the Hebrew Scriptures. Christian belief that (1) applies to pagans stems from New Testament texts and philosophy. I consider some broadly philosophical arguments that all idolatry is wrong, no matter by whom. I then argue that (2) rests inter alia on a robust doctrine of “general revelation,” and suggest some of what must go into that doctrine if it is to support (2).