Romans 1:2-3 God promised this good news about his Son ahead of time through his prophets in the Holy Scriptures. His Son was descended from David.
Paul was set apart for God’s good news. The good news is not new news. Ever since the beginning of time, the Old Testament has been pointing to the same person.
If you read the Old Testament from Genesis forward, you will see the stories of the past generations that show that humans are sinful and that God always provides a way for their sins to be forgiven.
God was pleased with the sacrifice of a substitute for the sins of men. In Genesis, Abel sacrificed innocent animals to God as worship. Abraham was about to sacrifice his only son, Isaac when God provided a substitute animal for the sacrifice. God instructed the people of Israel who were slaves in Egypt to mark their doors with the blood of a lamb on the top beam and the two side posts so that when the angel of death visited Egypt, he would pass over those homes and not harm anyone there. In the desert, Moses instructed the Israelites on all the sacrifices they should make to God for their sins. Eventually you see the Family line of King David and follow it genealogically until you reach Jesus.
There are prophecies all over the Old Testament about the messiah that was to come showing that he must suffer. They are so detailed that they explain that the messiah would be born in Bethlehem, would be born poor, would heal the sick, would ride into Jerusalem on a white donkey, would be betrayed for thirty pieces of silver by one of his friends, would be tried in an illegal court, would be beaten beyond all recognition, would be crucified, would have none of his bones broken, would be buried in a rich man’s tomb, and would rise again after death.
The good news is that all of this was foretold and that it wasn’t that Jesus was martyred for his beliefs. It’s not that he was a good man who had bad luck. It is that Jesus was the plan all along. God’s plan was to provide the perfect substitute as a sacrifice for the sins of man. That sacrifice had to be sinless and had to die voluntarily. God takes the form of a man and is born by human means on earth, lives like a human yet is free from sin, then quietly and without a struggle goes through the worst six hours a person could possibly endure until he dies. But Jesus’ death was the substitute for your sin. That is what the gospel is all about. Jesus died in your place. He was buried and then to prove that he is God, raises himself up from being dead to die no more and now is alive in flesh and blood with a transformed body in heaven.
Christianity is the message that all this was done on your behalf and Jesus’ death and resurrection mean that if you are a part of his kingdom, your body will one day die, but it will be resurrected at some point. Christ’s gospel is that he wants everyone to be a part of his kingdom and that membership in that kingdom is free. You can’t earn it by being good. You can’t buy your way in. You can’t barter for it. The only thing you have to do is believe in Jesus Christ as Lord of your life and the only means of being able to be in His kingdom, then repent from living your life for yourself and start living it for Him. He is the only path to God.
The fact that Jesus was descended from David makes him the heir to the throne as the rightful king of Israel. Jesus is in fact more than that. Jesus is the head of his Kingdom. One day, in the future, his kingdom will encompass the whole earth. You have been chosen to be in his kingdom. It is strictly up to you to decide whether or not you will be a part of it.