Islam and Christianity have common origins. They are first cousins, both heirs to the Greco-Roman civilisation and the Judeo-Christian tradition. For European Christians, Muslims are not strangers they are more like a branch of the same family: via the Christians of the East, Islam encountered the legacy of ancient Greece; through the Christians and Jews, they discovered the Biblical tradition. It is no accident that they share common spiritual ancestors. Abraham is regarded as a progenitor in all three religions.

The differences and the separate elements are mostly focused on, when looking at the three Abrahamic religions of Islam, Judaism and Christianity. However, upon closer inspection of the roots, beliefs and scriptures of the three faiths, one quickly discovers and overwhelming amount of commonalities, far exceeding the similar prophets, characters, stories and actors in the respective texts.

All religions find the unifying element to be true, that God revealed himself to Abraham. The Patriarch also is the founder of a lineage of holy figures in all three religions. In Judaism he is seen as the founder of the Covenant, which describes the holy relation between man and God and the father of all Jews. In Christianity, Abraham is the ancestor of Jesus and the father of the faith. In the Muslim World, the Prophet Mohammed also descended from Ibrahim. In several surahs of the Koran Abraham is named as a friend of God. His faith in God is to serve as an example for the Muslims and all believers.

Therefore Abraham is a major character in the creation of all three faiths, all of which came to uphold a strictly Unitarian view of god, a transcendent, paternal and almighty creator of the universe. All three faiths also share not only the belief of how the world came to be, but also how it will end – with the resurrection of the dead. Both Christianity and Islam believe in Judgement Day, where all sentient beings receive justice for their deeds in the form of punishment or praise.

All religions also see the way to salvation, transcendence and to be a good believer in praising and pleasing their god, opposed to seeking spiritual enlightenment through philosophy or meditation.

Many of the Abrahamic religions have customs and characteristics in common. Representations of God are not allowed, man consists of a mortal physical body and an immortal spiritual soul which are connected for the duration of only one lifetime, started by God infusing the breath of creation in the individual and ending it in death.

This similarity of the faiths, their origins and practice prove that a peaceful coexistence and a parallel practicing of the faiths is possible as we experience in the next Legacy, in Al-Andalus at the time of the Convivenca and in the Berber-Arab-Norman culture of Sicily.