"Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, “Brothers, what shall we do?” 38 And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit." (Acts 2:37-38)

Here, Peter is preaching to the locals of Jerusalem who had just witnessed Jesus' death and resurrection. He's telling them that Jesus was in fact the Messiah, the very one they'd been waiting for. They're devastated that they crucified Him, and rightly so, even though the Book of Revelation tells us Jesus' death was the plan. Even before the foundation of the world, the weight of it should still impact us. It impacted the Jews that day so they repented. That means they turned from their sins and to Jesus and they got all the things that come with knowing Jesus: baptism into a new life, the Holy Spirit as a guide, and a promise. They also got the joy of knowing Him because He's where the joy is!