A friend in Ireland once met a little Irish boy who had caught a young bird. The poor creature was trembling in his hand and seemed very anxious to escape. The gentleman begged the boy to let it go, but he said that he would not for he had chased it for three hours before catching it.
The gentleman tried to persuade the boy but without success. Eventually, he offered to buy the bird and the boy agreed on a price. Then the gentleman took the poor little thing and held it out in his hand. The boy had been holding it very tightly, for he was stronger than the bird.
The bird sat for a time, scarcely able to realize the fact that it had got liberty; but in a little while it flew away, chirping, as if to say to the gentleman, "Thank you! Thank you! You have redeemed me."
That is what redemption is—buying back and setting free. So Christ came back to break the chains of sin, to open the prison doors and set the sinner free. This is the good news, the gospel of Christ.