The doctrine of the Trinity is the central Christian teaching about God. Christians believe that there is only one God, but in that one God are three distinct divine Persons—the Father, the Son (Jesus Christ), and the Holy Spirit—who possess equally and eternally the same divine nature. The early ecumenical councils took care to define the mystery of the Trinity with great preciseness because the mystery of God, obviously, is the most important of the mysteries of faith. During the early centuries of the Church’s life, many individuals denied elements of what Christians believed concerning the Trinity. Some claimed that Jesus was not really God; others rejected the divinity of the Holy Spirit; and some presented a very faulty understanding of God the Father. Belief in the Trinity is one main belief that distinguishes Christians from their Jewish and Muslim brethren.