Why can't people who pervert the gospel see what the verses about a cursed gospel actually say?

Les explains that this inability to see is tied to condemnation. He recounts an old booklet by radio pastor J. Vernon McGee, copyrighted around 1971, where McGee rehearsed a conversation with a Moody Bible Institute president—either Dr. Sweeting or Culbertson, as Les recalls. At an LA Bible conference in 1971, that president said he could never envision the apostasy of the Church at that time, and he had no idea the Church would be in such apostasy short of being in the tribulation. Les notes that was over twenty years ago and asks what he would think today, saying they could not handle it. Les says we have been programmed to see this creeping in and just roll with it, so the apostasy is now alarming. In that condition, people who pervert the gospel cannot see what these verses say, because they are under the condemnation of being accursed for perverting the Gospel.