[rob74]

Actually, when you say that someone is on a crusade, you usually do mean that he is involved in some kind of holy war (be it for an actual religious topic, e.g. against abortion, or for something that can be considered a religion, such as an extreme adept of a programming language - see also "evangelist"). So it's not about physically fighting, but still "fighting for some strongly-held belief" in a more general sense.

...maybe you mean "cruise"?

[hsn915]

The GP comment was highlighting that 作戦 includes the character for "war".

Now, in the case of "crusades", the word has very negative connotation in Arab/Muslims countries. So, when George Bush said the war on terror was a "crusade", the vast majority of political commentators in the Arab world took this literally as religious war between the Christian and Islamic civilizations.

[justsomehnguy]

Actually, when someone means the religious crusade when this is not implicitly understood from the context it is usually spelled as 'religious crusade'.