The two religions are too diametrically opposed for there to ever be total peace between the two. Islam would at minimum, have to abandon Jihad in a military sense and do away with discriminatory rules/laws/attitudes against Christians and Jews within Caliphates. Islam isn't willing to do so, given that their rules are supposed to be unchanging so as to not be perceived as corruptable or to stray too far from what Muhammad established.
Muhammad unfortunately, was a warlord who was bent on trampling over most (if not all) who opposed him or were in his path. This is what the historical record supports. Tons of previously Jewish/Christian lands were conquered for Islam on a permanent basis, so that is a starting point for why Christianity wouldn't condone any further Muslim advances into their remaining territories or will oppose anything that could risk strengthening Islam again if its to the non-Muslim world's detriment.
