| The Trinity is the
Christian doctrine that God is a being who exists,
simultaneously and eternally, as a mutual indwelling of
three personalities the Father, the Son (incarnated as
Jesus) and the Holy Spirit. Since the 4th century, in
both Eastern and Western Christianity, this doctrine has
been stated as "three persons in one God," all three of
whom, as distinct and co-eternal beings, are of one
indivisible Divine essence. The doctrine also teaches that
the Son himself has two distinct natures, one fully divine
and the other fully human, united in a hypostatic union.
Support of the doctrine of the Trinity is
known as Trinitarianism. Most denominations within
Christianity are Trinitarian, and regard belief in the
Trinity as a mark of Christian orthodoxy.