“‘Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.’ Now when they heard this, they were cut to the heart, and said to Peter and the rest of the apostles, ‘Men and brethren, what shall we do?‘” (Acts 2:36-37).
The message that they heard was painful to hear. It cut them in their hearts. Thayer says of the original word, “to prick, pierce; metaph. to pain the mind sharply, agitate it vehemently: used esp. of the emotion of sorrow.” Jesus was raised from the dead (Acts 2:32). He was (is) now both Lord (ref. to authority, Luke 6:46; Matthew 28:19) and Christ (ref. to the promised Messiah, Luke 24:44; John 5:39; 7:31). However, they had crucified Him (Acts 2:36). They cried out, “What shall we do?” They cried out because of their belief. They cried out because of their guilty conscience.
A sense of guilt can be good. It prompted those on Pentecost to cry out, and respond (Acts 2:37-38, 41). It prompted David to confess his sin (Psalm 32:3-5). Jesus said, “Blessed are those who mourn, for they shall be comforted” (Matthew 5:4).
Consider this story: “A woman came down the aisle in tear. The preacher received her and let her mourn over her sins. A friend came up to comfort her. Thinking she was helping, she said, ‘Oh dear, we all make mistakes.’ The preacher turned to the lady’s friend and said calmly but sternly, ‘Go make us some coffee!’ He later explained to the friend, ‘Mary was trying to die, and you wouldn’t let her.’ We can become enablers, helping others avoid mourning” (Woodroof, Sayings That Saved My Sanity, pp. 20-21). It is appropriate to mourn over sin.