"Love and faithfulness meet together; righteousness and peace kiss each other," (cf. Psalm 85:10, NIV).
"All things come to pass of necessity." (John Wycliffe).
Jesus prayed in the Garden of Gethsemene to be delivered from His forthcoming Passion if at all possible, but nevertheless conceding and relinquishing to the Father's will and plan from all eternity. Jesus willingly and obediently went to His death and had both the power to lay down His life and to take it up again, even choosing the exact moment He expired (cf. John 10:17-18). In other words, He chose to die for us and wasn't forced into it--it would be on His terms.
Jesus had prophesied of His blood being necessary for the New Covenant (as the blood of the covenant (cf. Matt. 26:28) to take effect as the Testator. In the Old Covenant, there had been a constant reminder of sin and continual sacrifices were necessary to look forward to His crucifixion in God's eyes. It is necessary in wills and testaments for the death of the testator to put it in effect. Jesus' blood sealed the deal! If the blood of Abel spoke volumes to God then how much more the very blood of the perfect Lamb of God that takes away the sin of the world. Note that only Christ qualified to foot the bill and pay the price.
Our salvation is free to us, but not cheap, it cost Jesus everything He had and we must surrender our all to Him as Lord of our lives Jesus made His sacrifice to end all sacrifices because it was perfect and of infinite value. Therefore it was sufficient to redeem all of us of our sins. When He said, "Tetelestai," or "It is finished [paid in full]" it meant that Christ's work was done: salvation was now a done deal! Christ paid the ultimate sacrifice for our sins and even if we gave all we could or have, it would not be enough to satisfy the wrath of God--He is God's Suffering Servant. But our best is not good enough! The only reason the cross accomplished the righteousness of God is that Jesus is God as well as man and died in our place for what we deserved.
All of us are as bad off,, but not as bad, as we can be spiritually or in dire straits in God's eyes and our righteousness is as filthy rags to Him. All of our righteousness is His gift to us, not our gift to Him. We have nothing to offer Him but brokenness and strife (the sacrifices of God are a broken and contrite heart). In other words, we are bankrupt in God's economy and must appeal for mercy and grace; not getting what we do deserve (hell) and getting what we don't deserve (heaven). Good for us that Christ thought that He would rather have us than his life. We are "to die for!" We must reckon this in light of the fact that God didn't owe us salvation and didn't need to satisfy His holiness and it would've been just to condemn every sinner. It's the mercy and grace of God that He had mercy on anyone at all.
We mock Christ and belittle His Passion when we try to earn our way to heaven, especially by keeping the Law. "If righteousness could be gained through the Law, Christ died in vain." (cf. Gal. 2:21). In fact, if we rely on the Law for righteousness, we are under a curse (cf. Gal. 3:10). None of us is capable of abiding by the perfect Law of God and need someone to obey it for us and be our Substitute. God accepts vicarious obedience! Jesus didn't just do a good deed in dying for people but took on our full penalty due us for our sins and became sin for us, but not a sinner. As Isaiah 53 says, He was crushed for our iniquities, bruised for our transgressions, and by His stripes, we are healed.
Christ didn't just die to be our example, though we are to follow in His steps (cf. 1 Pet. 2:21) nor was it just a moral example or lesson from God of Him exercising justice in some kind of moral universe to teach us some lesson. It was necessary for Him to suffer these things and then enter into His glory, as He said. Jesus wasn't just some martyr and champion for a good cause either! The concept that the crucifixion was just to satisfy God's government of the world to see that justice is served is also erroneous because it would only exhibit God's righteousness but not save anyone. Christ was no innocent victim either who got trapped or tricked by the wicked Pharisees and Pilate. But "He became obedient to the point of death," (cf. Phil. 2:8). He never asked us to feel sorry for Him but to believe in Him. And Christ's death was no accident of history either or some fluke of injustice, for He was guilty in the sense that He was assuming our sins.
And God planned this event from all eternity and even used the evildoers to do it, though it was still voluntary, they did as written of the including Judas (cf. Acts 2;23:4:28): "This man was handed over to you by God's deliberate plan and foreknowledge," "They did what your power and will had decided beforehand should happen." Christ didn't deserve the cross as if He had done anything wrong and it was His karma or was reaping what He sowed. But the reality or truth is that "the LORD has laid on Him the iniquity of us all," (cf. Isaiah 53:6). Crucifixion wasn't even an honorable way to die and this concept is rejected by Muslims as being too repugnant and undignified for God.
Some will say that since God is love, He should freely forgive us; however, He is also just and holy and sin offends Him and its price needs to be paid; death God did show His love by laying down His life while we were incapable of any righteousness of our own. We are all born "in Adam," or in solidarity with him and under condemnation as we are not only sinners, but it's our nature, birthright, and freewill choice to sin. If Christ had not died and also conquered death by rising from the dead we'd still be in our sins! Christ paid our full and due penalty and the only thing we contribute is our sin and need. We reckon that God is now both just and justifier (cf. Romans 3:26).
The climax and central fact of history is the crucifixion and subsequent resurrection of Christ. If this is not as God tells us it is the biggest and cruelest hoax in history, but if true it's the most wonderful truth, even in that we now know what love is; that Jesus laid down His life for us. (cf. 1 John 3:16). Soli Deo Gloria!