Jn. 2:21. He was speaking of the temple of His body.
Jn. 2:22. When therefore He was risen from the dead, His disciples remembered that He had said this, and they believed the Scripture and the word which Jesus had spoken.
And it is not surprising that the Jews did not understand the words of Jesus, nor did the disciples. For them there were two greatest difficulties: one — that the matter of the resurrection is very hard to comprehend, all the more so since it was entirely unknown to them; the other — that He who lives in the body is God. However, after the resurrection the disciples understood and believed the Scripture. Which Scripture? Both every Scripture that foretells the resurrection, and, as the clearest, this one: "You will not leave my soul in Hades" (Ps. 16:10), and this one: "The Lord desires to cleanse him of his wound and to show him light" (Isa. 53:11). For these passages of Scripture very clearly foretell the resurrection. Apollinaris attempts to find here a defense for his heresy. Wishing to confirm that the Lord's flesh was without a soul, he says: "The flesh is called a temple, and a temple is soulless; therefore, it too is soulless." Thunder-struck and dizzy fool! You would perhaps make the Lord's flesh into wood and stones as well, since the temple is made of them?! When you hear the Lord's words: "My soul is now troubled" (John 12:27) and "I have power to lay down My soul" (John 10:18), how do you understand them? If you say that this is spoken not of a rational and intellectual soul, then where will you place the words "Father! into Your hands I commit My spirit" (Luke 23:46)? Will you understand even this as referring to an irrational soul? And this: "You will not leave my soul in Hades" (Ps. 16:10), how does it seem to you? But perish you along with those who share your opinions.
Jn. 2:23. When He was in Jerusalem at the feast of Passover, many, seeing the miracles which He performed, believed in His name.
When Jesus was at the feast, some apparently believed in His name; but their faith was unsteady. For, attending to Christ for a time not as God, but as a God-bearing man, they again fell away even from this most insignificant faith. And that they were such is evident from what follows below.
Jn. 2:24. Jesus Himself did not entrust Himself to them, because He knew all people.
Jn. 2:25. And He had no need for anyone to testify about man, for He Himself knew what was in man.
"He Himself," it says, "Jesus did not entrust Himself to them" and did not transmit the full teaching, as to those who did not truly believe, penetrating into their hearts (Ps. 93:11; Jer. 17:10) and knowing what was in them concerning Him. For it was not hidden from Him what the thought was in each person who apparently believed.