The European Christians were the first to develop the doctrine that the entirety of mankind must believe in one God, their God, and be converted to one religion, their religion. They were the first to proclaim that all Gods, except their own, should not be worshipped because they were false. They were the first to send Jesuit priests to all parts of the world to preach their religion and inspire conversions. They were the first to use political and military power to make people give up their traditional religious beliefs and accept the Christian faith.
Before the rise of Christianity in Europe (during the fourth century, the age of Constantine the Great), nations fought wars for all kinds of reasons: to capture slaves, conquer territory, plunder, to capture natural resources and critical trade routes. But they never fought in the name of their God. They never tried to impose their religion on people in the countries that they conquered.
For instance, when Alexander the Great conquered the Persian Empire, he did not try to force the Persians to convert en masse into the Greek religion. He allowed them to carry on with their religious beliefs. In fact, to endear himself to the Persian community, Alexander and his generals themselves converted to the Persian religion. When Alexander went to Egypt, he proclaimed that he venerated the Egyptian Gods, and that he was himself an Egyptian pharaoh. The Egyptian nobles loved him when he appeared before them attired as a pharaoh.
The Roman Empire followed the policy of never interfering with the religious beliefs of the people in the territories that they conquered in Europe and North Africa. In pre-modern India, the Hindu kings used to follow a very tolerant religious policy. Buddhism, an offshoot of Hinduism, was born in India and through the work of Buddhist monks it became a major religion in several nations—Japan, China, Thailand, Mongolia, Sri Lanka, Burma. The Mongol king Genghis Khan never imposed his religion on the masses in the territories that his Mongol army conquered.
Even the Islamic rulers did not follow the policy of converting their subjects in the territories that they conquered in Europe (Al-Andalus Empire). From 711 to 1492, Al-Andalus was under the rule of Islamic monarchs but there was hardly any conversion to Islam. In her book, The Ornament of the World, Professor Maria Rosa Menocal notes that Christians were the majority community in Al-Andalus; the financial system and International trade in Al-Andalus was dominated by the Jews who constituted 10 percent of the population.
In 1095, when the crusades were announced by Pope Urban II to liberate the Holy Land, Christians were in a majority in the Middle East and North Africa, and the Byzantine Empire, which was more than 90 percent Christian, was the most powerful state in the region. The religious zeal and violence of the invading crusaders drove the masses in this region into the arms of the Islamic preachers and rulers. By the end of the thirteenth century, the crusaders were driven out of the Middle East, and in the fifteenth century, the Byzantine Empire fell to the Ottoman Turks.
By the end of the nineteenth century, when one-third of humanity had been converted, Christianity’s hold on the West began to unravel. In the 1970s, historian Ram Swarup observed that, due to the rationalist review done by Europe’s thinkers, “Christianity had had its teeth knocked out in the modern West…” He believed that when the work of Europe’s thinkers reached India, Christianity would cease to appeal to the Indian masses. He saw Islam and communism as the twentieth century’s powerful proselytizing forces.