I answer that, He properly atones for an offense who offers something which the offended one loves equally, or even more than he detested the offense. But by suffering out of love and obedience, Christ gave more to God than was required to compensate for the offense of the whole human race. First of all, because of the exceeding charity from which He suffered; secondly, on account of the dignity of His life which He laid down in atonement, for it was the life of one who was God and man; thirdly, on account of the extent of the Passion, and the greatness of the grief endured, as stated above (46, 6). And therefore Christ’s Passion was not only a sufficient but a superabundant atonement for the sins of the human race; according to 1 John 2:2: “He is the propitiation for our sins: and not for ours only, but also for those of the whole world.”... Christ’s satisfaction works its effect in us inasmuch as we are incorporated with Him, as the members with their head, as stated above (1). Now the members must be conformed to their head. Consequently, as Christ first had grace in His soul with bodily passibility, and through the Passion attained to the glory of immortality, so we likewise, who are His members, are freed by His Passion from all debt of punishment, yet so that we first receive in our souls “the spirit of adoption of sons,” whereby our names are written down for the inheritance of immortal glory, while we yet have a passible and mortal body: but afterwards, “being made conformable” to the sufferings and death of Christ, we are brought into immortal glory, according to the saying of the Apostle (Rm. 8:17): “And if sons, heirs also: heirs indeed of God, and joint heirs with Christ; yet so if we suffer with Him, that we may be also glorified with Him.” Summa Theologica, Part 3, Q 49.3 .