What does John 7:48 mean?

The ultimate form of spiritual arrogance is assuming that your sect, denomination, group, or clique is so pure that they cannot possibly be wrong, about anything. This is, in effect, exactly why the Pharisees are so enraged; men they sent to arrest Jesus instead remark on His impressive words (John 7:46). While others are debating evidence (John 7:31), or Scripture (John 7:40–42), the Pharisees have a single, simple reason to ridicule those who accept Christ: the Pharisees haven't believed in Him, therefore anyone who does is a fool. According to Pharisaical thought, only those blessed by God could obtain knowledge, and their knowledge was superior to everyone else's. Jesus, on the other hand, has already taught that a willingness to submit to God has to come before a person gains understanding (John 7:17).

The Pharisees' self-importance is so out of control that they will turn on one of their own. Nicodemus is the same man who approached Jesus in private (John 3:1), and made specific mention of miracles (John 3:2). At the very least, he seems to be a man interested in careful discussion. But even making such a suggestion earns him insults from his peers (John 7:52).

Before we look down on the Pharisees, it's important to remember that this mistake is repeated over and over again, even today. When we dismiss an argument or intentionally seek to discredit some claim, only because it comes from some "other" perspective, we're guilty of the same error.