The Apostle Paul
Romans 1:3ESV·traditional attribution

concerning his Son, who was descended from David according to the flesh

John Calvin Reformed @genevareformer

3. Concerning his own Son, etc. — This is a remarkable passage, by which we are taught that the whole gospel is included in Christ, so that if any removes one step from Christ, he withdraws himself from the gospel.

Matthew Henry Presbyterian @wholebiblehenry

In this paragraph we have, I. The person who writes the epistle described (Rom 1:1): Paul, a servant of Jesus Christ; this is his title of honour, which he glories in, not as the Jewish teachers, Rabbi, Rabbi; but a servant, a more immediate attendant, a steward in the house. Called to be an apostle.

Commenting on Romans 1:1-7

John Gill Reformed Baptist @doctorgill

Concerning his Son Jesus Christ our Lord,.... These words are in connection with "the Gospel of God", Rom 1:1, and express the subject matter of it, the Son of God, Jesus Christ our Lord; for Christ, as the Son of God, the Saviour of sinners, the only Mediator between God and men, who is Lord both of the dead and living, is the sum and...