The opening verses of Paul's epistle to the Romans stressed that the gospel of Christ was actually the fulfillment of that "which he had promised afore by his prophets in the holy scriptures" (v. 2). This promise was centered in God's eternal Son who had promised to redeem the world from sin and death.
To do this, He must become a man, "made of the seed of David according to the flesh" (v. 3), yet He also must be sinless in both nature and practice before He could become God's perfect sacrifice for sin. He must be perfect man--man as God intended man to be. He must be a "second Adam," created without sin, yet He must not fail as did the first Adam, being "in all points tempted like as we are, yet without sin" (Hebrews 4:15).
He must, therefore, be miraculously conceived. "A body hast thou prepared me" (Hebrews 10:5)--a perfect body unblemished either by inherited mutations or by a sin nature genetically inherited from His parents. Then, for nine months, His body would grow, finally to be born of the virgin and to live a life "holy, harmless, undefiled" until that perfect, sinless man could be made "one sacrifice for sins for ever" (Hebrews 7:26; 10:12).
But how would the world ever know that all of this was really true? How could lost sinners be assured that their Creator had now become their Redeemer?
By His resurrection from the dead--that's how! He has been "declared to be the Son of God with power . . . by the resurrection from the dead" (today's text). Jesus Christ is "that man whom he hath ordained;" and of this we can be sure, because "he hath raised him from the dead" (Acts 17:31). HMM