Yours is a good question
. The Christian bible does not say that there is only one God. It just says that, "
you will have no other god before you." If you are Jewish, Christian, or Muslem, then you worship the Jewish god, which they consider, eterenal, the Creator of all things, and the most powerful of all gods. Moses back in the day made a covenient with this Jewish god and a part of that covenient was that the Jewish people will worship "no" other god. Christians and Muslems both continue to follow that part of this covenient and today worship this same God and no other. There are other gods, it is just that if you agree to be Jewish, Christian, or Muslem and you worship any of those other gods you will be thumped
by the God that Mose's covenient was made with. From the Christian and Muslem standpoint you may be thumped anyway if you do not worship that God. But, the jury is still out on that and a lot of folks are still waiting to see what really happens.
Is there only one god? Absolutely not. You always have a choice to worship any god that you wish to as long as you have never declared yourself of the Jewish, Christian, or Muslem faith. If you have declared yourself of one of these faiths and you worship any other god, you will be thumped
.
This is because the God of those faiths is a very jealous God who is not to be taken lightly.