Trinity

The Christian doctrine of the Trinity (Trinitas, from trinus "threefold") holds that God is one God, but three coeternal consubstantial persons or hypostases—the Father, the Son (Jesus Christ), and the Holy Spirit—as "one God in three Divine persons". The three persons are distinct, yet are one "substance, essence or nature" (homoousios). In this context, a "nature" is what one is, whereas a "person" is who one is. The subset of Christianity that accepts this doctrine is collectively known as Trinitarianism, while the subset that does not is referred to as nontrinitarian (see also Arianism). Trinitarianism contrasts with positions such as Binitarianism (one deity in two persons) and Monarchianism (no plurality of persons within God), of which Modalistic Monarchianism (one deity revealed in three modes) and Unitarianism (one deity in one person) are subsets. While the developed doctrine of the Trinity is not explicit in the books that constitute the New Testament, the New Testament possesses a "triadic" understanding of God and contains a number of Trinitarian formulas. The doctrine of the Trinity was first formulated among the fathers of the Church as early Christians attempted to rationalize the relationship between Jesus and God in their scriptural documents and prior traditions.

Bio from Wikipedia - See more on en.wikipedia.org Text under CC-BY-SA license