One moment defined old-school evangelicalism more than any other -- the altar-call ritual in which the Rev. Billy Graham urged sinners to come forward and repent, accept God's forgiveness and be born again. 

For decades, crusade choirs sang "Just As I Am," which proclaims: "Just as I am, and waiting not to rid my soul of one dark blot, to thee, whose blood can cleanse each spot, O Lamb of God, I come, I come." 

So evangelical activist Tony Campolo knew he was grabbing heartstrings as he referenced this gospel hymn when announcing that he had changed his beliefs on marriage and homosexuality. 

"As a social scientist, I have concluded that sexual orientation is almost never a choice," said the 80-year-old Campolo, for decades an influential voice on Christian campuses. "As a Christian, my responsibility is not to condemn or reject gay people, but rather to love and embrace them, and to endeavor to draw them into the fellowship of the Church. 

"When we sing the old invitation hymn, 'Just As I Am,' I want us to mean it." 

With this nod, Campolo underlined crucial questions in heated debates linked to the emerging evangelical left: Since the movement called "evangelicalism" lacks a common structure and hierarchy, who decides what the Bible says about repentance and forgiveness? Who decides when acts cease being sinful and become blessed?