We are not serving the same God. The gods which people serve are dependent on how they worship god. We cannot say that we are serving the same God when we are having different beliefs. What could be the reason for diversities in our mode of worship if we were serving the same God? So, the scenerior is very clear. It is obvious that we have different gods.
There are so many gods but there is the true God. The nations of the earth serve many kinds of things. Some of their gods are the works of their hands. These are idols. Idolatry is not accepted by the true God of the Bible. If something is in contrast to the other, how could you say that they are the same? We are not serving the same God.
In the various religions of the world, there are contradictions in the way they worship their gods. Some people do not believe in Jesus Christ the Son of God. They argue that God did not marry, so he wouldn't have a son. They do not accept that Jesus died for our sins and resurrected. All these are contradicting so, we are not serving the same God.