The US has to be most concerned about Xianity. They are by far dominant, and do by far more damage. I won't speak for the OP, but for me all religion is comparably ridiculous. I'll slam Islam just as fast as Xianity, but Islam really isn't much of a threat in the US. Just not enough foot soldiers, not enough influence. Congress is overrun with xians, and they make policy. THAT is a threat. There are only a handful of muslims there, and they have very little influence or power.

Judaism, xianity, and islam are -at their core- worshiping the same deity. There is no reason to believe in that deity, so they are varying degrees of ridiculous. And if you want to attack hinduism, or others, I'm game. Confidence is something you can't demonstrate is ill-advised, and making important decisions based on that is folly. But hindus aren't powerful enough to threaten us either. Our primary problem is xians, and especially the fundies who think that freedom of religion only applies to them.