Any doubts about whether the Glasgow Airport attack was by Islamist ideologues or not were dispelled by the witness who reported that he heard one of the terrorists, his clothes on fire, shouting "Allah! Allah!" as he fought off the ambulance man who was trying to help him.
This reminds me of something that happened to my father in World War Two. As he was an outstanding pilot, he served with Air Sea Rescue. One night he went out and rescued from the sea a Nazi who had been shot down. The Nazi then tried to shoot him.
Islamists and Nazis seem to have a lot of things in common: loathing of Jews, baseless belief in their own superiority, a degree of reckless hate of which Tolkien's orcs would have been proud, are just three of them. It is not insanity because they are not delusional, in the sense of out of touch with reality. But it is something like insanity.
I don't know what Gordo means by evil, but it seems to me that those who choose to destroy and harm instead of to build and help, are, in some profound sense, defective. (Which is the opposite of what people who have been ruled by dictators seem to think: that kindness is weakness. A big mistake.) Is it that they have failed to develop the ability to empathise? Is that what was wrong with Saddam Hussein and his horrible sons?
It must be terrible for families who have to try to comprehend how their children have turned into fanatics.