What does it mean that Jesus knew what was in man (John 2:25)?

In John 2:25, the apostle writes that Jesus “himself knew what was in man” (ESV). Jesus knew what was in man because He is omniscient and knows everything about everyone.

The context of John’s comment that Jesus knew what was in man is the account of Jesus trip to Jerusalem during the Passover Feast (John 2:23). During that time, Jesus performed various signs and miracles, leading many people to believe in His name. “But Jesus on his part did not entrust himself to them, because he knew all people and needed no one to bear witness about man, for he himself knew what was in man” (verses 24–25, ESV). Jesus’ knowledge of the people was not a matter of intuition or instinct; His knowledge of what was in man was rooted in His divine insight as the one-and-only Son of God. As God, Jesus had supernatural understanding into their minds, hearts, and souls.

Several other passages in the Gospels also show that Jesus knew what was in man. Examples include His supernatural knowledge of Nathanael’s character in John 1:47–48; the Samaritan woman’s personal history in John 4:29; His enemies’ thoughts in Luke 6:8; and Judas’s treachery in John 6:64.

Every sign and miracle that Jesus performed was designed to reveal God’s glory and lead people to saving faith (see John 2:11). Many at the Passover Festival responded to the miracles but did not have genuine faith, and Jesus knew it. Instead of understanding and accepting the person and work of Christ, they were grossly enamored with the spectacle of the miracles themselves. Having a superficial faith in Jesus is different from having a deep, genuine, and authentic faith: “The hour is coming, and is now here, when the true worshipers will worship the Father in spirit and truth, for the Father is seeking such people to worship him” (John 4:23, ESV).

Since Jesus knows all people, including what is in their heart, “He did not need any testimony about mankind” (John 2:25). We see a similar knowledge attributed to God in Jeremiah 17:10: “I the Lord search the heart and test the mind, to give every man according to his ways, according to the fruit of his deeds” (ESV). Similarly, 1 Samuel 16:7b reminds us that “man looks on the outward appearance, but the Lord looks on the heart” (ESV). As God incarnate, Jesus sees beyond superficial professions of faith and straight into the deepest recesses of our hearts.

The apostle’s emphasis on Jesus’ omniscience in John 2:25 lays the groundwork for subsequent teachings and interactions. In John’s Gospel, Jesus continuously stresses the need for saving faith and a wholehearted commitment to Him: “If you abide in my word, you are truly my disciples, and you will know the truth, and the truth will set you free” (John 8:31–32, ESV; see also John 15:5). True disciples will abide in His word; false disciples will not (1 John 2:19).

Jesus’ knowledge of our hearts is not a standalone fact unrelated to anything else; it is tethered to the idea of judgment, a theme that John develops more fully in later passages (e.g., John 5:22–23). As believers, we have “crossed over from death to life” (John 5:24). But for those who do not believe in Him, “God’s wrath remains on them” (John 3:36). Do you choose life or death?