After Jesus came back to life He told His disciples to go and tell as many people as possible about Him.

Mark 16:

14 Still later he appeared to the eleven disciples as they were eating together. He rebuked them for their stubborn unbelief because they refused to believe those who had seen him after he had been raised from the dead.

15 And then he told them, “Go into all the world and preach the Good News to everyone. 16 Anyone who believes and is baptized will be saved. But anyone who refuses to believe will be condemned. 17 These miraculous signs will accompany those who believe: They will cast out demons in my name, and they will speak in new languages. 18 They will be able to handle snakes with safety, and if they drink anything poisonous, it won’t hurt them. They will be able to place their hands on the sick, and they will be healed.”

19 When the Lord Jesus had finished talking with them, he was taken up into heaven and sat down in the place of honor at God’s right hand. 20 And the disciples went everywhere and preached, and the Lord worked through them, confirming what they said by many miraculous signs.