What does Luke 11:45 mean?

Jesus is eating at the home of a Pharisee (Luke 11:37). Pharisees were considered the most law-abiding sect of ancient Judaism. Lawyers, also called "scribes," are experts in the Law. They can be of the sect of Pharisees or Sadducees. If Sadducees, they know everything about the Mosaic law. If Pharisees, they are also experts in the Oral Law: extra-biblical regulations that scribes of past centuries added to the Mosaic law and which Pharisees follow closely.

One of the regulations in the Oral Law is ceremonially washing one's hands before eating bread. When Jesus did not do this, His host was astonished. Jesus responded by describing, in detail, how rinsing one's hands or following any manmade rule in public only hid that the Pharisees' hearts were filled with a wickedness comparable to death (Luke 11:38–44).

These lawyers are most likely in the sect of the Pharisees; Sadducees would not have cared about ritual washings and, it appears, rarely stray from Jerusalem. The lawyer's comment isn't necessarily defensive; it's a warning. Lawyers are very well-respected in the culture and Jesus is on dangerous ground.

Jesus turns His attention to the lawyers. He starts by pointing out the injustice of the laws their predecessors created. Then He equates them with the Jews of the Old Testament who murdered God's prophets. It's no wonder the Jewish religious leaders conspire to destroy Jesus (Luke 11:46–54).