The first proof is from Psalm 2:7 —“You are My Son, Today I have begotten You.” It establishes that Christ in the flesh is the Second Person of the Godhead seated at the Father’s right hand.
The second proof is from 2 Samuel 7:14 — “I will be a Father to Him And He shall be a Son to Me.” This quote comes from the Davidic Covenant made between God and David, which establishes an heir that will reign from David’s throne forever. Thus, Paul uses this quote to establish Jesus, the Son of God as the Heir of David, who will reign (Isaiah 9:6-7).
- For a child will be born to us, a son will be given to us; And the government will rest on His shoulders; And His name will be called Wonderful Counselor, Mighty God, Eternal Father, Prince of Peace. There will be no end to the increase of His government or of peace, On the throne of David and over his kingdom, To establish it and to uphold it with justice and righteousness From then on and forevermore. The zeal of the Lord of hosts will accomplish this. - Isaiah 9:6-7
Additionally, the titles of Father and Son establish the relationship between the First and Second Person in the Godhead. These two titles reveal the unique relationship that exists between them. No angel has ever enjoyed such a relationship as the one between the Father or the Son.