Today's verses are Mark 5:18,19: "As he (Jesus) was getting into the boat, the man who had been possessed with demons begged him that he might be with him. And he did not permit him but said to him, 'God home to your friends and tell them how much the Lord has done for you, and how he has had mercy on you.'" The demoniac, now free and in sound mind, sees his deliverer, Jesus, getting into a boat, ready to leave this Gentile area. He begged Jesus that he could join his group and be a part of his inner circle. Jesus didn't permit it. Rather, he sent him home to go and tell his family and friends what the Lord had done and how he had had mercy on him.
Many churches today are using an evangelistic strategy of "Come and see." They want their people to invite their family and friends to "come and see" what's going on in their worship services then, prayerfully, they will come to faith in Christ.
There's certainly nothing wrong with this strategy. However, it appears the strategy Jesus most often used was not "come and see" but "go and and tell." After experiencing the life-transforming power of Jesus, it's the responsibility of the newly changed person to go and tell what Jesus has done for you.
That's what Jesus told the now-free demoniac. He went home to this area called the Decapolis. As a Gentile territory, Jesus didn't have to face the growing hostility of the Jewish authorities. He didn't have to worry about misinterpretations of his Messiahship among these people. Therefore, as opposed to earlier places in the Scripture where Jesus demanded healed people to be quiet, here he gave the man freedom to proclaim.
Also, by proclaiming Jesus' power and grace in this area, it set the stage, after the Resurrection, for the Gospel to be proclaimed in this Gentile area. People would have known the name of Jesus because of this event and been more willing to receive the message of salvation.
And what was his message to be? He was to tell his family and friends how Jesus had had mercy on him. Mercy. It means not getting what we deserve. There was nothing meritorious the demoniac had done to deserve Jesus' healing grace. But it was given, freely, mercifully, to this man.
That same kind of mercy from Jesus has been given to all of us who believe. We don't deserve the Cross of Christ. We don't deserve our sins to be forgiven by grace through faith. There is nothing meritorious within us to deserve mercy. But it is given to us, freely, graciously and mercifully. That is the message we proclaim to those who don't know him: I'm a sinner, far from God. But God mercifully, through Jesus, died on the Cross to forgive me of my sins. Now he gives me salvation as a free gift, by grace through faith.
Come and see is a strategy that works. There is nothing wrong with it. But go and tell is what Jesus wants from all those whom he has touched with his mercy.