@cicerone imposter,
Crusaders are all too apt to be single-minded and to fail to recognise the nuances contained in their ideas and fearful of exploring the limits and the dangers of them.
Take uxoriousness as an example. It is all very well as an idea and as a strategy for being thought Mr Nice Guy in genteel circles but when the nuances of it are explored it can easily become debilitating and thus dangerous.
Scientific materialism partakes of this philosophical weakness.
In both cases it is usually denied that there is anything to explore further than the expression of the ideas. In that sense it is truly "out of this world" as all crusaders, perhaps, need to be.
Even obedience to the law if taken too far can be dangerous.