IV. Christ's passion provided a saving mystery and an example for us to follow
And what is suggested to our hearts by these and many other references, save that we should in all things be renewed in His image Who, remaining “in the form of God,” deigned to “take the form” of sinful flesh? For all our weaknesses, which come from sin, He took on Him without sharing in sin, so that He felt the sensation of hunger and thirst and sleep and fatigue, and grief and weeping, and suffered the fiercest pangs up to the extremity of death, because no one could be loosed from the snares of death, unless He in Whom alone all men's nature was guileless allowed Himself to be slain by the hands of wicked men.
And hence our Saviour the Son of God provided for all that believe in Him both a mystery and an example, that they might apprehend the one by being born again, and follow the other by imitation. For the blessed Apostle Peter teaches this, saying, “Christ suffered for us, leaving you an example that you should follow His steps. Who did no sin, neither was guile found in His mouth. Who when He was reviled, reviled not: when He suffered, threatened not, but gave Himself up to His unjust judge. Who Himself bare our sins in His body on the tree, that being dead to sins, we may live to righteousness.”
Source: Sermons (New Advent)