Trinity

The Trinity is the Christian doctrine holding that God is one in essence and exists in three distinct persons: God the Father, God the Son (Jesus Christ), and God the Holy Spirit. The three persons share one divine substance, so they are not three gods but one God in three persons.

The word comes from the Latin "trinitas", meaning "threefold" or "triad". The idea was developed by early Christians from the late second century onwards, and the Church fathers elaborated it to explain the relationship between Jesus and God as presented in the scriptures and earlier traditions. The doctrine was firmly established in the fourth century by the First Councils of Nicaea and Constantinople, which made it an integral part of the creed.

Writers who have explained the doctrine generally distinguish two aspects: the unity of the divine essence and the distinction of the three persons. Hilary of Poitiers summarised it as one God existing in three persons, in whom the Father and the Son share the same divine substance. Athenagoras of Athens described it as a unity of power with a distinction of persons. On this view, creation and grace are a single action shared by the three persons, each of whom manifests distinct attributes; hence the formula that everything is from the Father, through the Son, and in the Holy Spirit.

The doctrine is generally regarded as a mystery of faith rather than a conclusion reached by reason, and its formulation has been debated for centuries. Unitarians, modalists and other non-trinitarian groups have rejected it, while most major Christian denominations accept it today. Its theological study is called triadology or Trinitarian theology.