Judas must have come to Jesus with the genuine desire to believe and follow him, otherwise Jesus would not have accepted him. At least, we find nothing of distrust or resistance on the Lord’s part — and still less of any thought of the ‘necessity’ of receiving his traitor along with his other intimates. Therefore we must suppose that Judas really was well disposed. Like every other apostle, he brought his weaknesses with him. Peter also had his; he was impulsive; his heart and tongue were forever running away with him — to his great good as well as to his great detriment. He was inconstant. It took a real miracle of divine power to make of Peter “this rock” (Matt. 16:18). By nature he was far from rocklike. . . . Also John had his failings. Art and legend have misrepresented him. He was anything but the delicate, affectionate disciple of love. His mind soared higher than those of the other apostles, but he was a zealot too and capable of all kinds of impatience and harshness. We feel this when he calls down the fate of Sodom upon Samaria, and there are other passages in his writing that are terribly hard.

That he so often spoke of charity and understood it so deeply is possibly due to the fact that he did not possess it — at least not the charity of kindness, though there are also other varieties. . . . Also Thomas was not perfect. Jesus’ word to him about the blessedness of those who believe without seeing, suggests that at times he must have been close to unblessedness. . . . In the same way, Judas too had his weaknesses, and the Evangelist — John it is — describes one of them, probably the most conspicuous, with great sharpness: he loved money. Thus his faith had to struggle with avarice, his readiness to reform with inner bonds. Cupidity does have something degrading about it. A generous heart beat in Peter, for all his thoughtless impulsiveness, and in John’s fanaticism burned the ardor of genuine surrender. Even skeptical Thomas was honest enough to give truth its due, once it had been revealed. But in Judas there must have been a streak of meanness.

How, otherwise, could John call him hypocrite and thief? And how could Judas have conceived of such baseness as to seal his treachery with the kiss of peace? But the possibility of salvation was also in him; Judas had received the vocation of an apostle and could have been one. But his readiness to reform went lame. When this happened we do not know; perhaps in Capharnaum when Jesus proclaimed the Eucharist, and so many hearers, disciples among them, took offence and turned from him (John 6:60–66). Jesus’ most intimate circle must also have been deeply shaken, or he would not have asked: “Do you also wish to go away?” Not one of them was capable of belief in the fullest sense of the word. Peter dared the utmost of what they were capable when he rescued himself by a leap into blind trust: “Lord, to whom shall we go? Thou hast words of everlasting life” (John 6:68–69). We do not understand, but we believe in you, and for your sake we accept your words. Possibly this was the moment in which Judas’ faith went out. That he did not leave, but remained as one of the Twelve was the beginning of his treachery. Why he stayed, we do not know. Perhaps he still hoped to muddle through inwardly, or he wanted at least to see how things would develop — unless he already dreamed of profiting by the situation. – from The Lord