In Peter’s darkest moment, he denies that he even knows who Jesus is. I don’t criticize Peter for this, however. Despite a desire to respond differently, I suspect that if facing death, I could easily do the same thing.
Later, after returning to life, Jesus restores Peter to right relationship with him. Three times Jesus asks, “Do you love me?”
Three times – each one corresponding to one of Peter’s three betrayals – Peter confirms that he does indeed love Jesus.
Then, for Peter to show his love for his master, each time Jesus asks Peter to take care of Jesus’ flock, that is the Christian church.
Peter doesn’t realize the importance of repeating this exchange three times, that he must affirm his love for Jesus in equal number to his betrayals. Then, when his pledges of support offset his prior denials, Jesus can complete Peter’s restoration. Jesus concludes with the simple instruction, “Follow me.”
That’s the essential requirement of faith: to love Jesus and follow him. It’s that simple.