I'm sorry, how exactly is Christianity more rational, or gender-equal, than paganism? Or even Islam?
Christianity didn't prevent the Dark Ages. Nor did it prevent Communism or National Socialism.
Also, let's not forget that in many cases, it was the Christian Europeans who were the aggressors against the pagan Europeans, and colonized their territory. In most cases, if you leave out the originally non-European aggressors (Huns, Magyars, Mongols, Islamic Arabs etc.). It's not that I don't appreciate the things that came with Christianization, such as getting rid of human sacrifices, (re-)building a unified European political structure and civilization, giving new impulses to philosophical thought etc., but there were a lot of things lost in the process, including a lot of the indigenous cultural heritage. And Christianity also introduced some problematic new elements, such as the concept of original sin (basis for the current problem of self-loathing among native Europeans), or religious anti-Semitism.
Sure, and I'd rather be surrounded by armed, self-respecting Christians than by the self-loathing and hypocritical pacifists Christians that are much more common in this part of Europe. However the latter are also a product of fundamentally Christian thinking, and serve to demonstrate a big weakness in the belief system, just like Islam has its flaws.
And when Islamic missionaries spread the faith to Westerners, it often makes a lot of sense to them too (also, there are Muslims who convert to Christianity). This is because these people seek meaning in life and want to fulfil their spiritual needs, and there are certain religions that suit certain character types more than others. It's not a matter of one belief being more logical than the rest.