I believe in all. In different religions, God is termed differently though he is One and common to entire humanity. Christian term him as Father in Heaven, Muslims term him as Allah and in Hinduism there are several forms attributed to the one god. For example, a man can be a father to his children, dear to his wife, and brother to a sister and son to his parents. Each will accost him differently but he is the same person. Likewise in whichever way you call, God is God and he is common to whole humanity just like the Sun is common to the entire world.