Europeans viewed Islam as a threat and worked hard on stopping its spread. At that time Islam saw a great expansion in North Africa and even on the Iberian peninsula which was almost fully under the rule of Muslims. Later wars were fought and Muslims were pushed back down the peninsula into a small area that after a few centuries the new kingdom of Castile eliminated. So to summarize Christians in Europe did not like the Muslim expansion and as soon as they could they worked on eliminating them.
