I’ve seen Calvinists quote this (along with others like it) to demonstrate that the notion of limited atonement didn’t originate with Calvin or his followers. But I’m having a hard time tracking down the source. Neither Logos Bible Software nor the Internet have been able to get me any earlier than 1979.
Michael Horton quoted it twice in Putting Amazing Back into Grace: Embracing the Heart of the Gospel (Grand Rapids: Baker, 2002). Unfortunately, he didn’t cite his source. Even worse, he attributed it to two different people: Ambrose of Milan (c. 337–397) and Anselm of Canterbury (c. 1033–1109).
Ambrose, a church father, said, “If you die in unbelief, Christ did not die for you.” Don’t think that didn’t make people think twice about the offer of Christ! (118)
Anselm lost a lot of friends over this one:
If you die in unbelief, Christ did not die for you. (247)