2 Behold, you have heard that when our Lord Jesus Christ “was in Jerusalem at the Passover, on the feast day, many believed in His name, seeing the signs which He did.” “Many believed in His name;” and what follows? “But Jesus did not trust Himself to them.” Now what does this mean, “They believed,” or trusted, “in His name;” and yet “Jesus did not trust Himself to them;”? Was it, perhaps, that they had not believed on Him, but were feigning to have believed, and that therefore Jesus did not trust Himself to them? But the evangelist would not have said, “Many believed in His name,” if he were not giving a true testimony to them. A great thing, then, it is, and a wonderful thing: men believe in Christ, and Christ trusts not Himself to men. Especially is it wonderful, since, being the Son of God, He of course suffered willingly. If He were not willing, He would never have suffered, since, had He not willed it, He had not been born; and if He had willed this only, merely to be born and not to die, He might have done even whatever He willed, because He is the almighty Son of the almighty Father. Let us prove it by facts. For when they wished to hold Him, He departed from them. The Gospel says, “And when they would have cast Him headlong from the top of the mountain, He departed from them unhurt.” And when they came to lay hold of Him, after He was sold by Judas the traitor, who imagined that he had it in his power to deliver up his Master and Lord, there also the Lord showed that He suffered of His own will, not of necessity. For when the Jews desired to lay hold of Him, He said to them, “Whom do you seek? But they said, Jesus of Nazareth. And said He, I am He. On hearing this saying, they went backward, and fell to the ground.” In this, that in answering them He threw them to the ground, He showed His power; that in His being taken by them He might show His will. It was of compassion, then, that He suffered. For “He was delivered up for our sins, and rose again for our justification.” Hear His own words: “I have power to lay down my life, and I have power to take it again: no man takes it from me, but I lay it down of myself, that I may take it again.” Since, therefore, He had such power, since He declared it by words, showed it by deeds, what then does it mean that Jesus did not trust Himself to them, as if they would do Him some harm against His will, or would do something to Him against His will, especially seeing that they had already believed in His name? Moreover, of the same persons the evangelist says, “They believed in His name,” of whom he says, “But Jesus did not trust Himself to them.” Why? “Because He knew all men, and needed not that any should bear witness of man: for Himself knew what was in man.” The artificer knew what was in His own work better than the work knew what was in itself. The Creator of man knew what was in man, which the created man himself knew not. Do we not prove this of Peter, that he knew not what was in himself, when he said, “With You, even to death”? Hear that the Lord knew what was in man: “Thou with me even to death? Verily, verily, I say unto you, Before the cock crow, you shall deny me thrice.” The man, then, knew not what was in himself; but the Creator of the man knew what was in the man. Nevertheless, many believed in His name, and yet Jesus did not trust Himself to them. What can we say, brethren? Perhaps the circumstances that follow will indicate to us what the mystery of these words is. That men had believed in Him is manifest, is true; none doubts it, the Gospel says it, the truth-speaking evangelist testifies to it. Again, that Jesus trusted not Himself to them is also manifest, and no Christian doubts it; for the Gospel says this also, and the same truth-speaking evangelist testifies to it. Why, then, is it that they believed in His name, and yet Jesus did not trust Himself to them? Let us see what follows.
3. “And there was a man of the Pharisees, Nicodemus by name, a ruler of the Jews: the same came to Him by night, and said unto Him, Rabbi (you already know that Master is called Rabbi), we know that You are a teacher come from God; for no man can do these signs which You do, except God be with him.” This Nicodemus, then, was of those who had believed in His name, as they saw the signs and prodigies which He did. For this is what he said above: “Now, when He was in Jerusalem at the passover on the feast-day, many believed in His name.” Why did they believe? He goes on to say, “Seeing His signs which He did.” And what says he of Nicodemus? “There was a ruler of the Jews, Nicodemus by name the same came to Him by night, and says to Him, Rabbi, we know that You are a teacher come from God.” Therefore this man also had believed in His name. And why had he believed? He goes on, “For no man can do these signs which You do, unless God be with him.” If, therefore, Nicodemus was of those who had believed in His name, let us now consider, in the case of this Nicodemus, why Jesus did not trust Himself to them. “Jesus answered and said unto him, Verily, verily, I say unto you, Unless a man be born again, he cannot see the kingdom of God.” Therefore to them who have been born again does Jesus trust Himself. Behold, those men had believed on Him, and yet Jesus trusted not Himself to them. Such are all catechumens: already they believe in the name of Christ, but Jesus does not trust Himself to them. Give good heed, my beloved, and understand. If we say to a catechumen, Do you believe in Christ, he answers, I believe, and signs himself; already he bears the cross of Christ on his forehead, and is not ashamed of the cross of his Lord. Behold, he has believed in His name. Let us ask him, Do you eat the flesh of the Son of man, and drink the blood of the Son of man? He knows not what we say, because Jesus has not trusted Himself to him.
Source: Tractates on the Gospel of John (New Advent)