Outrage. The man who commenced a genocide escaped with no penalty. Disgrace. The swimmer who abused a woman and ruined her life got off with a sentence of only six months. Horror. The woman who committed fraud bribed the judge. The best judges are the ones who aren't swayed by bribes, and are committed to punishing a crime in accord with the seriousness of the crime.
Our hearts long for justice! We reel in pain at the shooter who shoots up a club or a theater, crying out for a proper punishment. In our personal lives, most of us have experienced the pain of being hurt by a loved one, betrayed by friends, wronged by those close to us. At those times, our hearts have one sharp desire: let justice roll down like a river!
If God is perfect in justice, He cannot let sin go unpunished. He cannot sweep abuse, bullying, tyranny, or murder under the rug. However, God loves this world of broken people! In fact, He loves us so much that before the foundation of the world, the Father, the Son, and the Spirit made a plan to provide a way out for humanity. The Son chose to represent all of humanity and took on Himself whatever consequences would fall on them. Since the penalty must correspond to the seriousness of the crime, and since God must oppose and reject all sin and evil, either man had to bear his crime before God or Jesus had to endure an infinite penalty.
So the eternal Son, perfect in glory, infinite in honor, became a man who suffered death on a Cross. He gave Himself up to the authorities of his day, and was unjustly condemned to death. Yet, Jesus knew what He was doing. By exchanging His honor as God for condemnation as a man, He paid the debt we owed to God. Jesus, on a Roman cross, took on Himself all sins. He bore God's wrath towards evil and evildoers, and died under the weight of it.
See, Jesus satisfied the demand for justice our hearts cry for. He paid the debt all people owed for their sin. He provided the "money" or payment we had to make for our sin against God. In doing that, God both satisfied the demands of justice and made a way for us to know Him. So what must you do to be "saved"--what must you do to know God forever? You must accept the payment Jesus made for you. The Bible says that you must "believe that God raised Jesus from the dead and confess with your mouth that Jesus is Lord"--that He is the Master of your life who you obey without compromise, and the Savior who rescued you. You must turn from your old way of living and trust Jesus' work for you, and Jesus' commands over you. In other words, you must do something that is incredibly hard but extremely liberating: give up. Give up running your life, and allow Jesus to undo the Fall. Allow Him to be the God of your life.
Jesus died for your sins and my sins, having willingly given himself up to the hands of humanity. Yet this is not how the story ends. On the third day after Jesus' death, the Father raised Him from the dead to end all suffering.