The reason why Muslims could not convert all India is because of the resistance of the Hindus and Sikhs, and not due to Islam. Islamic doctrine is very clear - all Muslims have to strive for conversion of non-Muslims to Islam.
Allah is indeed the word for God in Arabic, but this god is very different from the Hindu conception of God. The Hindu concept of God does not demand his/her/its followers to worship himself/herself/itself or risk burning in hell forever. In Hinduism, God is an experience to be located and discovered in one's own consciousness. The Islamic God has nothing to do with consciouness - it is mere believing in the deranged claims of a so-called prophet who was a mental patient.
