During the 7th century an Arabian religious leader named Muhammad ibn ‘Abdullāh began to spread the message of the Qur'an (Koran), which includes some traditions similar to those of the Christian and Jewish faith. This new faith, called submission or الإسلام (al-’islām) in Arabic, proclaimed the worship and obedience of a purely monotheist God or Allah in Arabic as the purpose of life, and Islam would ultimately prove to be the greatest challenge that the Christian Church would face during the Middle Ages. By the 630s Muhammad had united the entire Arabian peninsula under Islam, including the formerly Christian kingdom of Yemen.