For if by one man's offence death reigned by one; much more they which receive abundance of grace and of the gift of righteousness shall reign in life by one, Jesus Christ.) Death reigned by one - Death is here personified, and is represented as reigning over the human race; and death, of course, reigns unto death; he is known as reigning, by the destruction of his subjects.
Shall reign in life - Those who receive, retain, and improve the abundant grace offered by Jesus Christ, shall be redeemed from the empire of death, and exalted to the throne of God, to live and reign with him ever, world without end. See Revelation 1:5, Revelation 1:6; Revelation 2:7, Revelation 2:10, Revelation 2:11; Revelation 3:21.
If we carefully compare Romans 5:15 with Romans 5:17, we shall find that there is a correspondence between περισσειαν, the abounding, Romans 5:17, and επερισευσε hath abounded, Romans 5:15; between της δωρεας της δικαιοσυνης, the gift of righteousness, i.e. justification, Romans 5:17, and ἡ δωρεα εν χαριτι, the gift by grace, Romans 5:15; therefore, if we understand the abounding of grace, and the gift of justification, Romans 5:17, we shall understand the grace of God, and the gift by grace which hath abounded unto the many, Romans 5:15. But the abounding of grace, and the gift of justification, Romans 5:17, is that grace and gift which is Received by those who shall reign in eternal life. Reigning in life is the consequence of receiving the grace and gift. Therefore, receiving the grace is a necessary qualification on our part for reigning in life; and this necessarily implies our believing in Christ Jesus, as having died for our offenses, receiving the grace so freely offered us; using the means in order to get more grace, and bringing forth the fruits of the Spirit. Receive must here have the same sense as in Matthew 13:20 : He heareth the word, and anon with joy Receiveth it. John 1:12 : But as many as Received him, to them gave he power to become the sons of God. John 3:11 : Ye Receive not our witness. - See also John 3:32, John 3:33. John 5:43 : I am come in my Father's name, and ye Receive me not. John 12:48 : He that Receiveth not my words. John 13:20 : He that receiveth whomsoever I send, Receiveth me. John 14:17 : The Spirit of truth; whom the world cannot Receive. John 17:8 : I have given them the words which thou gavest me; and they have Received them. In all these passages it is evident that receiving and not receiving imply improving or not improving.