At first the Pharisees did not know what to make of Jesus. But that changed.It changed because he said things like this:
“I told you that you would die in your sins; if you do not believe that I am the one I claim to be, you will indeed die in your sins.” John 8:24
We can only imagine how angry this made the Pharisees.
They thought that their religion and their own works were the way to God. Jesus said that He was the true way to God.
They thought they could attain righteousness; actually they thought they had already attained it. They believed that violating the Law was the heart of sin.
Jesus says that unbelief in Him is the source and basis and definition of all sin.
Later in the same chapter (John 8) they say Jesus is demon-possessed; at the end of the chapter they try to stone him; later they will crucify him.
But then he proved how wrong they were.