It has often been pointed out all of the things that have occurred under the "guidance" of Christianity, through history, and the question has been asked, "Where has atheism been?" I thought that, perhaps it was time to put things into perspective.
During the Early Middle Ages and Middle Ages, the open espousal of atheistic views was rare in Europe, and atheism was a very uncommon, even dangerous, doctrine to hold. The charge of atheism was regularly used as way of attacking one's political or religious enemies, and the repercussions were severe. However, certain heterodox views were put forward by individual theologists such as Johannes Scotus Eriugena, David of Dinant, Amalric of Bena and William of Ockham, and by groups like the Brethren of the Free Spirit, and several writers mention that there were “not a few” (in the words of John Calvin) who denied the existence of God.
For most of the Middle Ages, religion was so universally dominant that it was not even believed possible that someone could deny the existence of God. Heterodox views were equally rare in the medieval Islamic world, although the 9th Century scholar Ibn al-Rawandi did go so far as to criticize the notion of religious prophecy (including even that of Mohammed), and maintained that religious dogmas were not acceptable to reason and must be rejected.
The European Renaissance of the 15th to 17th Centuries did much to expand the scope of freethought and skeptical inquiry, although criticisms of the religious establishment (such as those of Niccolò Machiavelli, Leonardo da Vinci, Bonaventure des Périers and François Rabelais) usually did not amount to actual atheism. As the scientific discoveries of Copernicus and Galileo became increasingly accepted, man's long-assumed privileged place in the universe appeared less and less justifiable. Progressive thinkers like Giordano Bruno, Lucilio Vanini and Galileo Galilei, bravely battling against the odds, were all savagely persecuted by the powerful Catholic Church of their time. Among those executed (often after torture) for the crime of atheism were Étienne Dolet in 1546, Giordano Bruno in 1600, Lucilio Vanini in 1619, Kazimierz Lyszczynskiin 1689 and Jean-François de la Barre as late as 1766.
With the religious infighting during the Protestant Reformation in the 16th Century, dissent of all kinds flourished, and some sects (such as the Anabaptists, Unitarians and Deists) developed much more humanist and less traditionally religious variants. Criticism of Christianity became increasingly frequent in the 17th and 18th Centuries, led by independent thinkers such as Thomas Hobbes, Baruch Spinoza and David Hume. The number of outspoken refutations to atheism during this period attests to the increasing prevalence of atheist positions, with some of the strongest anti-atheist apologists even attempting to deny the very existence of the movement they sought to crush. The British Blasphemy Act of 1677 specifically mentioned atheism and prescribed the death sentence for it.
So, when anyone questions why Atheists were not a stronger influence on history, the answer is very sim[ple: because that benevolent, loving religion Christianity saw to it through threats of imprisonment, loss of property, and even death that no one would ever even admit that they were an atheist.
So, whenever someone waxes poetic about all of the glorious things that Christianity has done for society through history, just remember that it has done so while also being the most repressive, oppressive, violent, and intolerant influences in history.