What had to be explained to these disciples was that there is a great problem in this world. It is the problem of human rebellion against God. This is the biggest thing in life to understand this. If you go through life without understanding this gospel message, you are ignorant of the meaning of life. You may be expert in all sorts of things, but if you don't understand this message you have missed the whole point of life. This human race is in absolute head-on rebellion against God. Ever since the fall of man, right back in the beginning, soon after the creation, man fell away from God. He rebelled, and he grasped his life for himself. Ever since then, we have been a depraved race, cut off from God. We each have this extraordinary piece of equipment called a conscience, whereby we intuitively, instinctively, know the difference between right and wrong. How is it that everybody has pretty well the same conscience? Yes, some people have their consciences are a little more finely tuned than others, but by and large everybody has this same standard. What a mysterious faculty! And yet, at the same time, in complete contradiction, I am morally weak. I cannot keep the standards of my conscience. My conscience comes to life and is very quick to notice when somebody else is off the track. But I myself cannot keep these standards. There is only one explanation for you being made the way you are, so different from the animals, with the power of reason, with the gift of conscience, and that is that you were made by God to be a moral creature. But you're a member of the human race which has fallen from God and is in rebellion, and now you are weak. You are covered in sin and guilt in the sight of God, and you are under the condemnation of God. We have an all-powerful God who is holy and perfect, and yet at the same time, he is full of love and compassion and tenderness. There are his creatures, the human race, in a state of rebellion, just selling out their lives for fleeting pleasure, and going into all eternity to be judged by a holy God. Abd yet our God is not only just and holy and therefore pledged to punish us for our sin, but he is also merciful and loving, and he longs to find a way out of this dilemma. How can he forgive us freely? How can he wash us clean from our sin and change us so that we love him? That i's what the gospel is all about. It is about how God has solved the problem of the human race. He has come himself into this world as the Son of God. He came not to set the human race an example. What good would that be to human beings who are rebels and determined to disobey God? Try with all my might and main, and I cannot even begin to copy him or to follow him. Christ’s life was a perfect example, but he did something much greater than that. He came to be a Saviour. He came in order to take my punishment, the guilt of my sin upon himself and bear away the pain and the punishment for me. This is how God finds it possible to forgive us. Something happened on that cross almost beyond human capability to understand. Jesus Christ stood in the place of his people, every human being who will ever be forgiven, and their sin, their guilt was put upon Christ. God the Father then poured out upon him somehow concentrated into the space of a few hours all the punishment which we should have suffered for our own sin. That is what the disciples had to have explained to them.