Do we all serve the same God? Well, let's consider it this way: if we were serving the same God, why are we still having religious conflicts? Why are we warring each other? When we consider it very well, it will be clear to us that we are not actually serving the same God. If we were serving the same God, we would have accepted each other's practice of worship without any reservations. But the truth being displayed before us proves that we are not serving the same God. Our gods are as different and numerous as our mode of worship differs.
What one is serving as God really matters. The power behind your destiny depends on who is the spiritual force behind you. Are you serving an animal (let's say something like a snake)? That will mean that your spiritual force is limited to a snake! If you worship a gravened image, then your god is such that can't move except someone carries it about. So what you worship or serve determines the spiritual backing following you.
The Lord Jesus Christ introduced the true God to us. He is the God who created the heavens and the earth. He is the one to whom we owe our lives. He is the one who is the living God. There are gods who are dead gods but the True God of the Bible is a Living God. It pays to serve the True God.