What Old Testament program was Peter still clinging to?
Peter still clung to the Old Testament prophetic program in which Israel first had to recognize her Messiah, after which the tribulation would unfold, followed by the King and the Kingdom. He quoted Joel about the last days, wonders, the day of the Lord, and salvation for all who call on the Lord.
Les explains that on the Day of Pentecost Peter saw Joel's prophecy being fulfilled and was still holding tooth and nail to the Old Testament program. That program required Israel to come to a knowledge of their Messiah, then the tribulation could unroll, and then they would have the King and the Kingdom. Peter should have stopped at verse 19 if he had known Israel would go into dispersion and God would turn to John, but he did not. He continued quoting Joel about wonders in heaven, signs on earth, blood, fire, vapor of smoke, the sun turned to darkness, and the moon to blood before the great and notable day of the Lord—the tribulation. Peter knew it had to come, yet he also quoted that whoever calls on the name of the Lord shall be saved, and that was Peter, not Paul.