It is generally agreed that the Battle of Poitiers (or Battle of Tours) in 732 was an important turning-point. The Muslims failed to conquer France.
Although at one time the Muslims ruled most of Spain, they never penetrated further east into Europe. Gradually the indigenous population of Spain fought back and reconquered Spain. The process took about 800 years, but the Muslims were formally evicted from Spain in 1492.
In the eastern end of Europe, it was the Byzantine empire that fought off the Muslim invasions. For 200 years (twelfth and thirteenth centuries) the crusades also resisted the Muslim incursions. The crusades were basically a stalemate: nobody won, but it meant the Islamic empire could not move westwards in that period. Even after the crusades ended, the Muslims had no real hope of conquering Europe until they had captured Byzantium, which they finally did in 1453.
The Ottoman Empire did attempt to expand into Europe, but most of the eastern nations - Romania, Bulgaria, Hungary, etc. - fought back. The Turkish army was defeated at the Siege of Vienna in 1683.
This is the how. As to the why - there is no one reason that can summarise a thousand years of history over a whole continent. However, most people are highly motivated to avoid being conquered. In addition, most of Christendom was convinced that it had a better way of life than Islam, and therefore fought desperately to avoid being brought under sharia rule.
Charles Martel stopped the advance of Islam into Europe. Had the Muslims continued to advance at the same pace they had up to that point, Christendom would have been subjugated within his lifetime and Christianity would have been a minority, clandestine religion in Europe.
Mainly through warfare
ANDREW WHEATCROFT has written: 'INFIDELS: THE CONFLICT BETWEEN CHRISTENDOM AND ISLAM, 638-2002'
Albania is the only country in Europe to have Islam as its dominant religion.
250000 or more than that people convert to Islam in Europe yearly.
Up to some extent the relationship between Europe and Islam is good.
I'd have to say Christianity for certain and with the rise of Islam, then Islam is number two.
The Battle of Tours effectively stopped the Islamic advance in Western Europe and allowed Catholicism (and Christianity in general) to survive as the dominant form of European religion and a potent opposition to Islam in the subsequent centuries.
Because people who claim to be acting in accordance with the teachings of Islam are bombing and terrorising people in Europe and America.
Historian Sir Edward Creasy, said "the great victory won by Charles Martel ... gave a decisive check to the career of Arab conquest in Western Europe, rescued Christendom from Islam, [and] preserved the relics of ancient and the germs of modern civilization."
It halted the Muslim invasions Charles Martel's victory at the Battle of Tours (variously dated 732 or 733) ended the Muslim advance into Europe that had begun in Spain in 711. This allowed most of Western Europe to remain untouched by Islam and secured the position of Christendom. The Muslims were pushed back into Spain thus keeping Western Europe under influence of Catholic Christianity
India, Europe, Islam, and china