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The Old Testament has been interpreted as referring to the Trinity by referring to God's word (Psalm 33:6), his spirit (Isaiah 61:1), and Wisdom (Proverbs 9:1), as well as narratives such as the appearance of the three men to Abraham. Russian icon of the Old Testament Trinity by Andrei Rublev, between 14 The doctrine of the Trinity was first formulated among the early Christians and fathers of the Church as they attempted to understand the relationship between Jesus and God in their scriptural documents and prior traditions. 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. Nontrinitarian positions include Unitarianism, Binitarianism and Modalism. This doctrine is called Trinitarianism and its adherents are called trinitarians, while its opponents are called antitrinitarians or nontrinitarians. In this context, the three persons define who God is, while the one essence defines what God is. The Christian doctrine of the Trinity ( Latin: Trinitas, lit.'triad', from Latin: trinus 'threefold') defines God as being one god existing in three coequal, coeternal, consubstantial divine persons: God the Father, God the Son ( Jesus Christ) and God the Holy Spirit, three distinct persons sharing one homoousion (essence).
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