They were stopped by Christian countries, who didn't allowed them to spread.
Explanation:
The most decisive battle was the battle of Poitiers
The Battle of Poitiers took place between the forces of Franks, led by Charles Martel and the Muslim army of the Umayyad Caliphate, led by Emir Abdullah Rahman.
Historians view this battle as the turning point of Christianity and Islam in Europe, and the Frankish victory played a major role in making Christianity the primary religion in this region.
