Prior verses, 23 and 24, subtly reveal the true nature of belief from a biblical standpoint. Because of what observers knew of Jesus from His miraculous signs, many came to believe in Him. However, Jesus made it His habit not to wholeheartedly “entrust” or “commit” Himself to them because He knew their hearts. Verse 24 indicates that Jesus looked for genuine conversion rather than enthusiasm for the spectacular. “Belief into His name” involves much more than intellectual assent. It calls for whole-hearted commitment of one’s life to Jesus.
Commentary from the MacArthur study Bible, notes for John 2:23,24.