At that time, Jesus said to the Pharisees: “Amen, amen, I say to you, he who enters not by the door into the sheepfold, but climbs up another way, is a thief and a robber. But he who enters by the door, is shepherd of the sheep.” And so forth. John1:1-10
Homily of St Augustine, Bishop
In the words of the Gospel which are read today, the Lord has spoken to us in Similitude’s of his flock, and of the door, by which the sheepfold is to be entered. Let the pagans, therefore, say: “We lead good lives!” If they do not enter by the door, what does that profit them in which them in which they glory? A good life is profitable to man if it leads to life everlasting, but if he is not to have life everlasting, what shall his good life profit him? Because they cannot be said to live well, who either through blindness are ignorant of the very end of all good living, or through pride despise the same. But no man has a true and certain hope of living forever, unless he acknowledge the life which is Christ, and enter by the door in the sheepfold.
Such men as these, therefore, for the most part, try to persuade men to live well, and yet not to be Christians. They wish to climb up another way, to steal and to kill; not, like the good shepherd, to keep and to save. And so there have been certain philosophers, holding many subtle discussions upon the virtues and vices; dividing, defining, reasoning out very clever arguments, filling volumes, airing their own wisdom with loud trumpets; who would even dare to say to others: “Follow us; keep to our sect if you would live happily.” But they did not enter by the door; they wished to destroy, to slay, and to kill.
What shall I say of these men? Behold, the Pharisees themselves were wont to read of Christ, and, in that very reading, their voices re-echoed Christ, they hoped for his coming, and yet did not recognise him while he was with them. They boasted that they themselves were among the seers, that is, among the wise, but they denied Christ, and entered not in by the door. Therefore, they chanced to lead them away to slay and to kill them, not to deliver them. So much for them. Let us look to those who glory in the name of Christ himself, and see whether even they by chance are entering in by the door. For there are countless numbers who do not only boast that they are prophets, but would have it appear that they are enlightened by Christ; yet they are heretics.
– St Augustine, Treatise 45 on John; from: An Approved English Translation of the Breviarium Romanum, Burns & Oates, London, 1964