Actually Jesus Christ coined the term "born again," as recorded in John 3:3, when he told Nicodemus "Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.”
Obviously you're not a student of history or you would know the term has been used since the time of Christ forward. For example St Augustine penned in A.D. 412:
"For it is not written, `Unless a man be
born again by the will of his parents' or `by the faith of those presenting him or ministering to him,' but, `Unless a man be
born again of water and the Holy Spirit.' The water, therefore, manifesting exteriorly the sacrament of grace, and the Spirit effecting interiorly the benefit of grace, both regenerate in one Christ that man who was generated in Adam" (Letters 98:2 [A.D. 412]).
Just one of many examples in antiquity where church leaders used the term born again in the context of the status of Christians.
"Born again Christians" was a term made up in the 1960s by American Evangelicals.