Why did Christianity spread to Europe by violence & Bloodshed while Islam only spread through war only in the Middle East and never in Europe?

Islam spread through war in the Middle East and North Africa, but the wars were in lands that were already populated by Muslims. But in Europe, Christianity was spread through war, violence, and bloodshed. The Goths had to be killed for not being Catholic while the Germans had to be killed for believing in their traditional religion. It only stopped once all of Europe was Christianized. On the other hand, Islam spread through war in the Middle East and North Africa, but only in lands that were already Muslim.