What was Othello's religion?
I guess you meant to ask the question as it reads now. Othello is a Christian fighting for Christians. He does not for a moment identify with the Muslim Turks that threaten Venice, his home of choice. However, when he speaks of the magic quality of the handkerchief he has given Desdemona, he inadvertently falls into ancient pre-Christian beliefs. As his despair increases, his pagan ancestry claims him. This can be seen in his speech about killing Desdemona as a sacrifice, and even in the way he chooses to take his own life. He once killed a Turk in the same way, so one might conclude that his chosen manner of death stands for the symbolic killing of the Turk that he doesn't seem to have succeeded in expelling from his innermost nature.