3 It is not without reason that we bring a critical judgment to the study of Scriptures where there are such discrepancies and contradictions. By thus examining everything, and comparing one passage with another, we determine which contains Christ's actual words, and what may or may not be genuine. For your predecessors have made many interpolations in the words of our Lord, which thus appear under His name, while they disagree with His doctrine. Besides, as we have proved again and again, the writings are not the production of Christ or of His apostles, but a compilation of rumors and beliefs, made, long after their departure, by some obscure semi-Jews, not in harmony even with one another, and published by them under the name of the apostles, or of those considered the followers of the apostles, so as to give the appearance of apostolic authority to all these blunders and falsehoods.
But whatever you make of that, as regards this verse, I repeat that I do not insist on rejecting it. It is enough for my position, that, as I said before, and as you are obliged to confess, before the coming of our Lord all the patriarchs and prophets of Israel lay in infernal darkness for their sins. Even though they may have been restored to light and liberty by Christ, that has nothing to do with the hateful character of their lives. We hate and eschew not their persons, but their characters; not as they are now, when they are purified, but as they were, when impure.
So, whatever you think of this verse, it does not affect us: for if it is genuine, it only illustrates Christ's goodness and compassion; and if it is spurious, those who wrote it are to blame. Our cause is as safe as it always is.
Source: Reply to Faustus the Manichaean (New Advent)