Early in Jesus’ ministry, many people believed on Him - but Jesus did not entrust Himself to them.
Now when He was in Jerusalem at the Passover, during the feast, many believed in His name when they saw the signs which He did. But Jesus did not commit Himself to them, because He knew all men, and had no need that anyone should testify of man, for He knew what was in man. (John 2:23-25)
Many people saw the signs Jesus did, and they “believed in His name.” We might think, “That’s wonderful! Many people are believing in Jesus!”
But Jesus knew what was in their minds, and He did not entrust Himself to them, or He did not have “faith in their faith.”
How could this happen?
The issue here is not whether their faith was genuine or not, but what its object was. These individuals, after seeing the miracles, believed Jesus to be the Messiah. They most likely saw in him a political-eschatological figure of some sort. That does not, however, mean that their concept of “Messiah” was the same as Jesus’ own, or the author’s. - NET Translator Notes
The NET Translator’s notes fit with what happens later in John. After Jesus fed a multitude, they tried to take Him by force and make Him king (John 6:14-15). They saw Jesus as the one who could fulfill what they wanted.
Jesus made it clear throughout John that He had come to do the Father’s will, not the nation’s (John 5:17-19; 6:38).
The problem of the crowd from John 2 was that when they saw the signs Jesus did, they started thinking of how Jesus could do for them what they wanted. When Jesus kept teaching what God’s will was, many stopped following Him (John 6:66).
They knew what He could do - but He wouldn’t do what they wanted Him to do.
Do we do this?
Do we approach the Lord’s church with a desire to get what we want out of it? This happens in politics all the time - politicians use religion to get certain groups of people to vote for them. Their lives demonstrate they don’t really care about what Jesus offers - they are only interested in what they can get out of it all.
Sometimes people will move to a new church because they like what that church can offer them. But as soon as they hear something taught from God’s Word they don’t like - they move on down the road.
Do we have this attitude toward the Lord?
If we do, we may very well have the same type of faith as the crowd had in John 2 - a faith in which Jesus had no faith.