Do you mean which is grammatically correct? The correct structure in English is "I believe in God", which means "I have faith that a being called 'God' exists."

thats the spirit... cowboy...

Hello Nika, It is usually " I believe in God" which means having faith in God and being sure of his existence. If you said " I believe God" which is not so commonly used , it means literally you believe what he says is true.

"I believe in God" is correct.

I believe in God I devote to God