As far as we know, it had never occurred to any of the OT saints that God had a Son. Should the Jewish people have understood these passages referred to the Lord Jesus, especially as our Lord spoke so often of His Father? Despite His overwhelming miracles and despite (or perhaps because of) the godlike words He spoke, He was condemned to an unconscionable execution.
At his Pentecost sermon, Peter concluded with, "Let all the house of Israel therefore know for certain that God has made Him both Lord and Christ, this Jesus whom you crucified."
The Jewish people who heard this message responded by saying, "What shall we do?"
What could they mean by that? They had already done it. They had done the worse thing that had ever been done. They had crucified the Beloved Son, the One so well pleasing to the Heavenly Father.
"What shall we do?" It was an outrageous question.
But filled with the Holy Spirit, Peter responded to them, "Repent...for the forgiveness of your sins."
We then read, "and there were added (to those who loved the Lord and who were loved by Him) about 3000 souls.
Amazing love. Amazing forgiveness. The Father forgave them. Until that Pentecost moment, they had no idea what they had done.