Before Jesus was crucified and resurrected, he preached the gospel. He told Nicodemus that he must be born again. I wonder what this meant to the people who heard him as the Holy Spirit had yet to be poured out on believers. How could someone be born again when at that time regeneration by the Holy Spirit was not possible yet?
Regeneration by the Holy Spirit is not what makes a person born again. It’s what happens after a person is born again. Being born again comes from believing that Jesus died for our sins and rose again (John 1:12-13).
Remember, Jesus was critical of Nicodemus for not understanding Him, saying, “You are Israel’s teacher, and you do not understand these things?” (John 3:10). Therefore He expected Nicodemus to understand the concept of being born again from the Old Testament. I believe He was referring to Ezekiel 36:25-26.
“I will sprinkle clean water on you, and you will be clean; I will cleanse you from all your impurities and from all your idols. I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh.”