Killing and raiding for resources instead of getting your own, and starting battles just to die in battle because you wanna enter Valhalla and the only way to enter is if you die fighting is some how more honorable than trying to stop Christian persecution in the holy land. And to finally fight back against the Muslims after 800 years of trying to avoid war.

Christianity is also a religion of selflessness (trying to imitate Jesus Christ) so they don’t fight just to enter heaven.