Almost every religion I can think of only worships one god, yes. However, depending on who you ask, not every religion worships the same god, and no one can agree on which one is the true one and which ones are false. Then again, there are others who will claim that they're really one and the same, and that everyone is just splitting hairs.

To complicate matters, there's also your run of the mill frauds and charlatans. If they can't find a god to suit their purposes, then they'll simply pull a new one out of thin air.

But like I said, my own nation wasn't one for worship, other than a few fringe elements. I can only give you my observations. If you're looking for personal experience, then I'm afraid you're out of luck.