Getting back to the topic. Here in the States, the only people who would find it rude to not drink are the people whose idea of a good time is to get beyond drunk. In a social gathering, there really is no need to drink if you don't want to. If anyone tries to pressure you, just say one of three things:
1) Sorry, I don't drink.
2) Sorry, but I'm driving later.
3) Sorry, I just haven't found a beer I enjoy.
The third is one I rectified by asking bartenders what their favorite beer on tap was, and ask for a sample. Not quite your taste? Say so, and explain why. They will usually be able to find a beer for you by the fourth sample. If they do, buy one, and only one. Savor it. Make sure it is to your taste.