All religions do not serve the same God. If there is only one God, it is reasonable to assume He wants to be worshipped in only one way, which He will make known to man. Jesus is God. He dwells in His children and so they have the assurance that they are serving the only God. He also give us a deep peace and great joy.

I agree. Even in biblical times there was other religions, which is idolatry, and other pagan religions. Read what God wrote with His finger in the 10 commandments