Summary: The sufferings of Jesus were unique in that He suffered once for all, the just for the unjust. But we are still sometimes called to bear up and endure grief, suffering unjustly. Our model was laid down in the patient pattern of His sufferings.
The Apostle Peter uses his address to domestic servants (1 Peter 2:18) to illustrate the calling of all Christians to share in the sufferings of Christ. “For this is grace,” he quite literally says (1 Peter 2:19): this is acceptable; this is thankworthy - if out of consciousness of God, and in conscience toward God - we bear up and endure grief, suffering unjustly. Not only are some people maliciously punished for doing good, as might be the case of the domestic servant under a tyrannical head of the household, but any one of us might fall under various afflictions in the course of doing good.
Of course some of our sufferings can be traced directly to our own sins. Actions have consequences, and the servant breaking the household rules will be punished accordingly. If we are continuing a life of sin, and God continually buffets us for it - like waves beating against the seashore - what did we expect?
But if we continue firm and persevere in the face of unjust sufferings, “this is grace” (1 Peter 2:20): this is acceptable to God; this is thankworthy with God. This is, after all, our calling (1 Peter 2:21). The model was laid down in the sufferings of Messiah (Isaiah 53), and we are to follow in His footsteps.
If we ever think that our present afflictions are undeserved, then we must look to our example: who being free from personal sin (1 Peter 2:22) suffered uncomplainingly (Isaiah 53:7) for the sins of His people. He committed Himself to God - He gave Himself over to God - He surrendered Himself to God, who always judges righteously (1 Peter 2:23). Far from calling twelve legions of angels to His rescue (Matthew 26:53), He proved Himself willing to drink to the very dregs the cup of our just desserts (John 18:11).
In going to the Cross, Jesus bore the sin of many (Isaiah 53:12). Death and suffering are both consequences of sin. In His death we were made dead to sin, so that we might live to righteousness; our suffering is also brought to heel and healed in the wounds, the welts (Isaiah 53:5), which He bore on our behalf (1 Peter 2:24).
We were all like sheep going astray until the LORD laid our iniquity upon His suffering Servant (Isaiah 53:6). Only thus are we “now returned to the Shepherd and Overseer of our souls” (1 Peter 2:25). Peter would surely remember his own fall, and the Lord’s mercy in restoring him.
Let us be clear, in summary: the sufferings of Jesus were unique in that He suffered once for all, the just for the unjust (1 Peter 3:18). There is no lack of efficacy in the sacrifice of our Saviour, but the Apostle Paul by comparison speaks of “filling up that which was behind of the afflictions of Christ” for the church (Colossians 1:24). Just as Jesus had to suffer, so we are called to suffer.