On the day of Pentecost, Peter said, what? “Read the Four Laws”? Or “go to a convention for a weekend”? Or “take something to calm your mind down because you’re upset”? 

No; Peter said the same thing as Jesus and the same thing as John the Baptist, he said, “Repent!” (Acts 2:38) In Luke 3:8 it says John the Baptist began to preach and to say: "Repent"! And in [Mark 1:15] it says Jesus “began to preach and say,” what? "Repent"! 

- Leonard Ravenhill