Complex sentence: According to Hossein Nasr, Ali, the first Imam of the Shia and fourth Rashid Caliph in Shi'i and Sunni Islam, is credited with having established Islamic theology and his quotations contain the first rational proofs among Muslims of the Unity of God.
Split into simpler sentences: According to Hossein Nasr, Ali, the first imam (Shia view) and fourth Rashid Caliph (Sunni view), is credited with having established Islamic theology. His quotations contain the first rational proofs among Muslims of the Unity of God.