What is the problem if I believe that God is present in every human being and that he alone who serves all, is worshiping God?

If God is in every human being, God is present in yourself also. Then why should you serve all? You can serve yourself repeatedly. Instead of serving 100 people, you can serve yourself 100 times. In both cases, God is worshiped 100 times. In that case, every selfish fellow also is a real servant of God! If you say that God is divided into bits and every human being has a bit of God and unless you serve everybody the whole God is not served, this is absurd because there is only one God, who is indivisible. In that case, unless you serve all the human beings on this earth, the service to the whole God cannot be completed and this is practically impossible!