Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 19

Chapter 19.—Of Those Who Promise Impunity from All Sins Even to Heretics, Through Virtue of Their Participation of the Body of Christ.

So, too, there are others who promise this deliverance from eternal punishment, not, indeed, to all men, but only to those who have been washed in Christian baptism, and who become partakers of the body of Christ, no matter how they have lived, or what heresy or impiety they have fallen into.  They ground this opinion on the saying of Jesus, “This is the bread which cometh down from heaven, that if any man eat thereof, he shall not die.  I am the living bread which came down from heaven.  If a man eat of this bread, he shall live for ever.” 1533   Therefore, say they, it follows that these persons must be delivered from death eternal, and at one time or other be introduced to everlasting life.

Footnotes

John 6:50, 51.