Right, but the thing is..even if God exists, how do I know which religion is the ultimate truth. Jews don’t accept Jesus as the Messiah and Christians don’t accept Muhammad as the last prophet and muslims don’t accept Mirza Ghulam Ahmed as Mehdi. they all claim to know the truth. I can’t accept one religion to be the ultimate truth because we don’t know.
Besides, believing in God and following a religion are two separate things.