The third of God’s annual festivals (after the Feast of Unleavened Bread) is the Feast of Weeks, or Pentecost (Leviticus 23:16-21; Acts 2:1). This festival, also called the Feast of Harvest or First fruits (Exodus 23:16; Exodus 34:22), was also the day God first granted His Spirit to the New Testament Church of God (Acts 2).
After receiving the Holy Spirit, Peter stood up and preached to a great multitude of Jews. In verse 36, at the end of his sermon, Peter said, “Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.” verse 37, “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?” It is this moment that the painting pictures, the moment “they were cut to the heart.” The moment that God opened their minds to the need to do something. It was and still is the moment of conviction that leads to repentance and baptism. It is the seminal moment of conversion and the birth of the church.