How do we know that God is a Trinitarian being?

The doctrine of the Trinity is derived from various Scripture passages that collectively affirm the explicit roles of the Father, the Son, and the Holy Spirit as God. For instance, in Matthew 22:31-32, God speaks of Himself as the God of Abraham, Isaac, and Jacob, emphasizing His living relationship with His people. 1 John 5:7 states there are three that bear record in heaven: the Father, the Word, and the Holy Ghost; these three are one. This Trinity serves as the basis of our understanding of God's nature and His self-revelation as a covenant God.