In the opening verses of his first letter to the Thessalonian community, among the very earliest texts of the New Testament, the Apostle Paul refers to three dramatis personae, God and Father, our Lord Jesus Christ, and the Holy Spirit:
Paul, Silvanus, and Timothy, To the church of the Thessalonians in God the Father and the Lord Jesus Christ: Grace to you and peace. We always give thanks to God for all of you and mention you in our prayers, constantly remembering before our God and Father your work of faith and labor of love and steadfastness of hope in our Lord Jesus Christ. For we know, brothers and sisters beloved by God, that he has chosen you, because our message of the gospel came to you not in word only, but also in power and in the Holy Spirit and with full conviction.(1 Thess 1:1–5)
What is remarkable is that, even at this early stage, the community is clearly well acquainted with this triadic pattern. No explanation is offered; evidently none is necessary. The pattern is apparently already well established as the distinctively and typically Christian way of speaking of God.