Among the things religions can save people from is a burdensome sense of their moral imperfection—the sense of sin. Apparently sin was central to the salvation message of early Christianity. Paul put the theme front and center. “All, both Jews and Greeks, are under the power of sin, as it is written: ‘There is no one who is righteous, not even one.’”

Certainly not Paul. “I am of the flesh, sold into slavery under sin. I do not understand my own actions. For I do not do what I want, but I do the very thing I hate.… But in fact it is no longer I that do it, but sin that dwells within me. For I know that nothing good dwells within me, that is, in my flesh. I can will what is right, but I cannot do it. For I do not do the good I want, but the evil I do not want is what I do.”

Scholars differ over whether this is Paul’s self-appraisal or whether he is speaking generically about the human condition. Either way, this passage must have been consistent with his personal experience.

Indeed, seeing how Jesus could solve his problems with sin may have been Paul’s defining intellectual epiphany—the thing that turned him into a zealous organizer of the early church. Suddenly, in Paul’s mind, it all made sense. One man, Adam, had brought sin, and hence death, into the human race through his weakness, and now one man, Jesus, had through his strength, and through his death, offered release from sin and death. And it was all a sign of love. God, to whom humans had long made sacrifices, so loved humanity that now he sacrificed his son. Thus did a story with an unhappy ending—the story of a supposed Messiah who’d wound up crucified—become a compelling message of salvation and eternal life.