So the first thing he realized was even though he thought he was doing God’s will, he was wrong. Everything he was taught in Pharisee school was wrong.
In order to really know Jesus, we have to humble ourselves to know that what we think we know may be totally incorrect.
Are we that open to admit that what we know and believe might be wrong? In our desire to know Jesus better, are we open to the knowledge that all our preconceived notions might not be right?
If we want to know Jesus, and have a relationship with the God of the universe, we have to do that His way, and not the way we may have been taught.
The second thing is that he had to admit that Jesus was alive and was somehow associated with the God of Israel.
That is the stumbling block that scripture talks about.