He causes some people to be bitter toward God. He causes many others to be deceived on how to be saved. He blinds their eyes. There are many people that look like they are led of God, but they are not. They themselves think they are being led of God and deceive many.
Many people go to churches that have blind leaders of the blind.
It never occurs to most people that their ordained minister is, himself, on the way to hell. These blind clergy combine God s Word with deception and traditions. Multitudes of people attend these dead, ceremonial, entertainment, people-pleasing churches and are confident they will be in heaven when they die. It just never occurs to most people that their church is leading them to hell. They put their faith in their church or denomination and its half-truth doctrines.