What is the Trinity?

Three In One: The Mystery of the Trinity

Christianity holds that there is one God, but three persons—Father, Son, and Holy Spirit. This doctrine is known as the “Trinity.” The doctrine has been a difficult one to understand, and was a topic of great dispute in the Early Church. Nevertheless, it is a central tenet of Christianity, and what separates Christianity from other monotheisms.

The doctrine reached a swelling point in the fourth century, when Arius claimed that Christ was created by God the Father, and was not co-eternal with him. Eventually, the Council of Nicene was convened to address Arius’ claims. Led in part by St. Athanasius, it found Arius’ claims heretical and formulated the Nicene Creed to discredit and correct them. For the next 100 years, Church Fathers would defend the doctrine of the Trinity from Arian challenges that still existed. Yet, by about the end of the fourth century, the doctrine of the Trinity took on, more or less, the form that we have today.

Although the Nicene Creed gave an initial formulation of the doctrine, Christian theologians and philosophers have not stopped discussing the doctrine. Gathered here is a list of what different Christians have said about the doctrine. Arranged chronologically, they show the doctrine developed and changed over time. The texts can be difficult at times, but are often thought-provoking.

CCEL has other additional readings worth consulting: Written and compiled by Tim Perrine, CCEL Staff Writer