The ideological cause of the Benghazi bungles was ideological blindness, Jim points out:
The attack on the Benghazi embassy was not a terrorist attack. It was a conventional military operation by the uniformed and well equipped troops of an organization that frequently engages in terrorist attacks. They used truck mounted artillery, not box cutters, and were dressed as Al Qaeda armed forces, not civilians. If you cannot say “War with Dar al-Islam”, or even say “War with Radical Islam”, you cannot see Islamic armed forces.
No one seems able to say “uniformed”. They say that they were wearing “Afghan costumes”. But no one in Libya wears “Afghan” costumes except armed forces affiliated with Al Qaeda, thus the costumes clearly identify them as members of an organized military force, which is the Geneva Convention definition of a military uniform.
So Al Qaeda launched a conventional military attack on the US government, and the US government refused to fight back. That was scandal one. Scandal two was that the US government proceeded to lie about it, to fit it into what they wanted to believe, rather than what actually happened. Hence the cover story that the attack was a demonstration related to a video critical of Mohammed — that it was outraged civilians, or perhaps terrorists hiding amongst outraged civilians and using them as human shields.
This lie was not only intended to cover up the first scandal, but to enable them to continue to believe in a worldview that had been falsified by events. They lied to themselves, as well as to their opponents.