The original conversion of Europe to Christianity was not accomplished by the sword or by armies, it was accomplished by individuals like Patrick. Patrick was a Briton taken as child to be a slave in Ireland, who escaped but felt a call to return there and preach the gospel, and without arms or coercion and with only his voice, the gospel, and the Paraclete in his arsenal was used in the conversion of the nation. That kind of story was repeated throughout Europe as men like Augustine, Columba, and Boniface, went unarmed and often alone into the midst of pagan nations preaching the gospel and were eventually granted success, and that often at the same time that Islam was being spread by the Sword in the Middle East.
The difference between the two religions really was that one was spread by preaching and the other by the sword. For centuries Muslims have not been ashamed of that, in fact most Muslim histories proudly proclaim that it was Allah who gave them victory over their enemies. You see to Muslims, Christianity and its methods and message are weak. In personal witnessing to Muslims, I have been told outright that the message of a Savior who dies a humiliating death on the cross for the sins of others is weak and dishonorable. It is far better, I was once told by a Yemeni Taxi cab driver, to believe in Muhammad than Jesus, because only Muhammad was a great and strong fighter who led his armies to victory.
The message of Christianity, though is not victory through strength and self-reliance, but what the world would call victory through weakness and total dependence on God for salvation:
"For since, in the wisdom of God, the world through wisdom did not know God, it pleased God through the foolishness of the message preached to save those who believe. For Jews request a sign, and Greeks seek after wisdom; but we preach Christ crucified, to the Jews a stumbling block and to the Greeks foolishness, but to those who are called, both Jews and Greeks, Christ the power of God and the wisdom of God. Because the foolishness of God is wiser than men, and the weakness of God is stronger than men. For you see your calling, brethren, that not many wise according to the flesh, not many mighty, not many noble, are called. But God has chosen the foolish things of the world to put to shame the wise, and God has chosen the weak things of the world to put to shame the things which are mighty; and the base things of the world and the things which are despised God has chosen, and the things which are not, to bring to nothing the things that are" (1 Cor. 1:21-28)
your msessage is fascinating and revealing. I did not think Muslims would value strength as they do.
There is no doubt that to the people in today's Eurasia, Americas and New Zealand hate the idea of weakness and dependence on God.
They believe it leaves some inferior to others and left some poor and propertyless waiting for an afterlife that reason shows wrong. Hence the support for radical socialism and nihilism among the masses in these nations, who feel oppressed by the rich. Marxism, though as violent an ideology as Islam, was for a full seventy years spread by preaching and became the dominate belief of Europe's working classes when suffrage was not universal. (Of course, Marxism did spread by the sword when it could). Islam was spread by preaching for only a fraction of a decade.