Please you Muslim guys need to chill the fuck out. Don't make me bring out the history of the spread of Islam as comparison, cause it isn't pretty. It is no different than any other conquest or war based on religion, i.e using religion as an excuse and justification but truly all about power and wealth.
Oh you mean mainly through peaceful means, namely trade and missionary work? Also bringing about a golden era of unprecedented prosperity and scientific advancement for many years to come? Roman Catholicism was spread by the sword, the spread of Islam was violent at points, but ultimately is more comparable to the spread of Buddhism than Catholicism.
I am Roman Catholic fyi
Anywho, being that I am Roman Catholic, I feel obliged to bring up an important point:
The Church during the middle ages was unfortunately very political. When the Eastern Roman Empire asked
Anywho, being that I am Catholic, I'd say its important to point out that the original purpose of the crusades was to supply the Byzantine armies with supplemental troops to fight along with the Byzantines. Instead the greedy and un-united indivdual lords went about sacking Byzantium, vandalizing this, massacuring that. Ultimately, the Crusades were forgotten by the Muslims as petty squables compared to their internal fractures and subjugation by various nomadic groups
The middle ages are a dark time for the Roman Catholic Church where the clergy held political power in the lack of any large effective government.