John 8:30-32

Now we understand that God was not trying to convert these people. He was putting them through lessons for our behalf so that we can read these things and understand. We can begin to see that the level of faith that God is talking about is not a function of mere knowledge of God—mere knowledge of God's existence. There is more to it than that.

The key phrase is, if you abide, if you continue, if you live in His word. Now it is interesting that Jesus' response to these peoples' belief was to admonish them that His word was of value only as they were committed to it. Without commitment, they accepted what He said as being true, but they did not accept the implications of it for their lives.