and because he didn't need for anyone to testify concerning man; for he himself knew what was in man.
The omniscience of the Lord is stated by the apostle in this verse; and, from the fact of John's bringing that attribute into the foreground at this particular juncture, it may be inferred that some of Jesus' disciples were a little disappointed that Jesus did not at once place himself at the head of that great throng of "believers" who had been so easily convinced by his miracles.  Only in the true retrospective reflection of the apostle so long afterward would the true reason for the Lord's refusal become clear. Something more than belief has always been a prerequisite for becoming a true follower of the Lord; and that throng of "believers only" had nothing of that "something more" always required.  That fatal lack was the thing Jesus discerned.  These were doubtless some of the same people who shouted, "Crucify him!" when the Lord stood before Pilate.  One additional thing, over and beyond faith only, required of all who would enter the kingdom of God is the new birth; and, appropriately, John next recorded Jesus' conversation with Nicodemus.