And the servants of the good man of the house coming said to him. Sir, didst thou not sow good seed in thy field? Whence then hath it cockle? And he said to them: An enemy hath done this. And the servants said to him: Wilt thou that we go and gather it up? And he said: No, lest perhaps gathering up the cockle, you root up the wheat also together with it. Suffer both to grow until the harvest, and in the time of the harvest I will say to the reapers: Gather up first the cockle, and bind it into bundles to burn, but the wheat gather ye into my barn. [Mt. 13:27-30]And this is no novel practice of the Church notwithstanding the complaints of Her critics. We may see this from Canto IX of the Purgatorio, where Dante has the Angel at the Gate say:
From Peter I hold these, who bade me err"Err in opening rather than in keeping fast:" that is, don't be too quick to judge. Now one may quibble as to how well such a principle might have been observed in Dante's time, but it surely is the case that he wasn't making it up: he was a faithful Catholic. And it is this principle that explains why we may rightly refer to Protestants as our brothers in Christ, just as the Church teaches today. For that matter we must apply it amongst ourselves, since we dare not presume that every Catholic born will Catholic die!
In opening rather than in keeping fast,
So men but kneeled to me without demur. [127-129; page 137 in the Sayers translation]