I believe Acts 2:37 reveals/confirms what the Lord Jesus Christ said about the Holy Spirit convicting the world. The unbelieving Jews were pricked in their hearts as Peter was preaching God's Word.
Peter did not pull any punches in his preaching. He flat out told them that Jesus was the Christ ... the Messiah spoken of by Joel, by David, approved of God by wonders and miracles. Peter told them of the resurrection and the ascension ... and he then told them in vs 36 God hath made that same Jesus, whom ye have crucified, both Lord and Christ.
so of course they were cut to the heart ... they were convicted in their hearts ... this is God's Word working in the hearts of the unbelievers ... and to this day God sends faithful believers to preach His Word to the lost, the Holy Spirit convicts people and they either believe or suppress the truth in unrighteousness.
God's Word is the Word of life ... God breathed life into His Holy Word ... that is why it is imperative that we speak God's Word ... not man's word ... or God's Word mixed with man's word.
Only God's Word is life and life-giving and God will only bring increase to the heart of those who believe God's Word.
Proverbs 4:20-23 My son, attend to my words; incline thine ear unto my sayings. Let them not depart from thine eyes; keep them in the midst of thine heart. For they are life unto those that find them, and health to all their flesh. Keep thy heart with all diligence; for out of it are the issues of life.
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@Cameron143, like many Reformed, thinks the idiom of being stabbed in the heart is circumcision - as he says. So, he has circumcision of heart before belief (circ > what shall we do? > believe). Good luck...
36 "Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ." 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?" 38 Then Peter said to them, "
Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins;
and you shall receive the gift of the Holy Spirit. 39 "For the promise is to you and to your children, and to all who are afar off, as many as the Lord our God will call." 40 And with many other words he testified and exhorted them, saying, "Be saved from this perverse generation." 41 Then
those who gladly received his word were baptized; and that day about three thousand souls were added to them. 42 And they continued steadfastly in the apostles' doctrine and fellowship, in the breaking of bread, and in prayers. 43 Then fear came upon every soul, and many wonders and signs were done through the apostles. 44 Now
all who believed were together, and had all things in common, 45 and sold their possessions and goods, and divided them among all, as anyone had need. 46 So continuing daily with one accord in the temple, and breaking bread from house to house, they ate their food with gladness and simplicity of heart, 47 praising God and having favor with all the people. And
the Lord added to the church daily those who were being saved. (Acts 2:36-47 NKJ)
What's the order of salvation here?
Do we have to look further into Luke-Acts to see the order of salvation according to Luke or to those he speaks about?
Is v.37 really the circumcision of the heart? It doesn't say it is.