Constantine, moreover, was not yet a Christian when he uttered the appeal to conquer in the sign of the cross; and while the warrior kings of Israel may have drawn strength from the old Covenant in their small and local wars, the Christians of the new Covenant were to agonise for centuries over the issue of whether warmaking was morally permissible or not. Christians, indeed, have never found unanimity in the belief that the man of war may also be a man of religion; the ideal of martyrdom has always been as strong as that of the justified struggle and remains strong to this day. The Arabs of the conquest years were not caught on that crux. Their new religion, Islam, was a creed of conflict, that taught the necessity of submission to its revealed teachings and the right of its believers to take arms against those who opposed them. It was Islam that inspired the Arab conquests, the ideas of Islam that made the Arabs a military people and the example of its founder, Muhammad, that taught them to become warriors.