For what glory is it, if, when ye be buffeted for your faults, ye shall take it patiently? but if, when ye do well, and suffer for it, ye take it patiently, this is acceptable with God. For even hereunto were ye called: because Christ also suffered for us, leaving us an example, that ye should follow his steps: Who did no sin, neither was guile found in his mouth: Who, when he was reviled, reviled not again; when he suffered, he threatened not; but committed himself to him that judgeth righteously: Who his own self bare our sins in his own body on the tree, that we, being dead to sins, should live unto righteousness: by whose stripes ye were healed. For ye were as sheep going astray; but are now returned unto the Shepherd and Bishop of your souls. (1 Peter 2:20-25 KJV)
Do you ever feel like life is unfair? Were you in line for a promotion and the boss played favorites and promoted his buddy over you? Did you marry your highschool sweetheart with dreams of how wonderful married life would be only to find it was less than desirable? Have you been let go from your job because you are a Christian and refuse to go out and get drunk with your superiors? Has a friend or family member suffered serious illness or injury at no fault of their's? Look at the slaughter of Christians and others in the Middle East. Yes, we can say life is unfair from our perspective.
But wait. If we expect and demand fairness what would that look like? Was Jesus treated fairly? No. If life was all fair what affect would that have on our salvation? As sinners we are all deserving of Hell. If life were fair that's where we would all go. But Christ was treated unfairly, from our perspective, so that His people could be saved from Hell. He took the sins of His people upon Himself and took our punishment to make peace with God the Father on our behalf. No, it wasn't fair, but it was just.
Justice demands a price be paid for sin. The price is separation from God. Justice must be served. It was served on Jesus in our place. Fairness demands that all be treated equally. If fairness was the standard, then all would go to heaven, and heaven would be filled with sin and no longer would be heaven and none would be any better off than they are now or all would go to Hell. That would be fair.
So when we think we have been treated unfairly, think about the cross and how "unfairly" Jesus was treated. Praise God this world is not fair!