We are not all serving the same God. The realities before us proves that we are not serving the same God. There are differences in the way we practice our religious beliefs. So, going by that, it is clear that we are not serving the same God. The true God of the Bible does not teach contradictory messages. He is the God who spoke to Moses and all the apostles. He is not a contradictory God.
There are religions who do not believe in the Lord Jesus Christ. They do not believe that the Lord Jesus Christ is the Son of God. They argue that God has never given birth. They do not worship the Lord Jesus Christ. They reject the belief that the Son should be worshiped. That is not the same belief that we have in Christianity.
There are some christians who do not believe in the writings of the Apostle Paul. They reject the teachings of the new testament. They refuse to accept that as part of the doctrines of Jesus Christ. That is not the same as the true church of God. So, we are not serving the same God.
Some religions do not eat certain foods. Their gods prohibit them from eating those ones. They do not eat any food. But others are there who eat anything they want. So, we are not serving the same God.
What of people who do not believe in God at all? They are the gods of their lives. They do not accept the teachings about the existence of God. So, there are many different gods in the world just as there are many different religions.