The central core truth about God is that he is vital Life (with a Capital “L”) in a loving relationship and communion of three unique beings: Father, Son and Holy Spirit. Their existence together is active, dynamic, joy-filled, mutually affirming and self-giving to such an extent that the gospel of John tells us Jesus lives IN the Father and the Father lives IN Jesus. Other scriptures indicate this existence IN each other includes the Holy Spirit. The depth of that existence in each other is the epitome of unity and harmony such that they are one God – the Father, Son, Holy Spirit God.* God is both first diversity and first unity.
This relational God-life we’ve been talking about is so abundant and overflowing with love that God wants to share His life with others. That is and has been his purpose since before the creation of the world. That desire was and is the womb of creation. That same desire and purpose birthed God’s plan that humanity be reconciled back to him through Jesus (2 Corinthians 5:14-20). Ephesians 1:9-10 shows us that God’s ultimate purpose in Christ is to bring all things in heaven and earth together in unity under him. Jesus, ever in complete harmony with his Father, prayed the night before he was crucified that we would be brought to complete unity in him just as the Father is IN Jesus and Jesus is IN the Father.
God is a communion of love and he invites us into his loving God-life through Jesus.
* Dr. Gary Deddo, Doctrinal adviser and Senior Editor for Grace Communion International (formerly Senior Editor for Academic Publications for Intervarsity Press), carefully makes this distinction.There isn’t one big omni-God and then the Father, Son and Holy Spirit as some seem to think. There is one God and He is the Father, Son, Holy Spirit God.