Muslims are required to respect all those who are faithful and God conscious people, namely those who received messages. Christians and Jews are called People of the Book. Muslims are asked to call upon the People of the Book for common terms, namely, to worship One God, and to work together for the solutions of the many problems in the society. Christians and Jews lived peacefully with Muslims throughout centuries in the Middle East and other Asian and African countries. The second Caliph Umar, did not pray in the church in Jerusalem so as not to give the Muslims an excuse to take it over. Christians entrusted the Muslims, and as such the key of the Church in Jerusalem is still in the hands of the Muslims. Jews fled from Spain during the Inquisition, and they were welcomed by the Muslims. They settled in the heart of the Islamic Caliphate. They enjoyed positions of power and authority. Throughout the Muslim world, churches, synagogues and missionary schools were built within the Muslim neighborhoods. These places were protected by Muslims even during the contemporary crises in the Middle East.