Romans 1:1–4, Paul, a servant of Christ Jesus, called to be an apostle, set apart for the gospel of God, 2 which he promised beforehand through his prophets in the holy Scriptures, 3 concerning his Son, who was descended from David according to the flesh 4 and was declared to be the Son of God in power according to the Spirit of holiness by his resurrection from the dead, Jesus Christ our Lord…. [esv]

“Had you realized that the power that was necessary to make believers out of you and me is the same power that God used in bringing up His Son from the dead and in raising Him and seating Him at His right hand in glory? Many people seem to think that to believe the Gospel is easy and simple; that a man sits as a kind of judge of the truth. Someone comes and preaches the Gospel to him, and then after some considerations he decides whether he is going to believe it or not. He has the power to do either, they believe; and he just exercises this poiwer. But, says Paul, it takes the power that brought the Lord Jesus Christ from the grave to deal with that man and change him. Nothing less than that power must be exercised in a soul to enable it to believe and to be saved. Nothing less! The natural man is totally incapable of this, as Paul says in 1 Corinthians 2:14, ‘…neither can he know (the things of the Spirit of God) for they are spiritually discerned’. Were it not that grace is irresistable, not one of us would ever have believed the gospel.”
~ Martyn Lloyd-Jones. Romans 5 Commentary