In the 1700's, the idea of atheism emerged as a topic of debate in France. As a result, the topic has remained one of discussion every since, and the percentage of the world's population who believe in atheism rose to somewhere between 0.5% and 1%, where it remains today. Exact figures vary, but given the world's population, the number represents a significant quantity of people.
Those who promoted atheism in that era were Jean Meslier (whose atheistic book was published upon his death in 1729), Baron d'Holbach (who published in 1770, living until 1789), and Jacques-André Naigeon (publishing in 1768, and living until 1810). Only the latter-most of these three lived to see the unfolding of atheism in the mass executions of not only priests, but ordinary folk who professed belief during the French Revolution.
Those who refused to embrace atheism included Voltaire, Rousseau, and Francois Rabelais, although the last of these three actually lived just prior to, and not during, the attempt to popularize atheism. The mathematician and philosopher Rene Descartes was personally involved in his faith in God, but did not directly or publicly engage in the atheist debate.
Outside of France, others who declined to adopt the atheist viewpoint included Thomas Hobbes, Baruch Spinoza, and John Toland, among many others.
The defense against atheism's attack was based on the work of previous philosophers, many of whom lived long before this contentious phase of French history, but who anticipated many of the issues, and assembled cogent reasoning: Johannes Scotus Eriugena, Nicholas of Cusa, William of Ockham,William of Ockham, Leonardo da Vinci, and Niccolò Machiavelli.
The effect, almost three centuries later, is that France's atheism rate is more than twice the world average; in fact, France has the highest atheism rate in the world - even more than Russia, China, or North Korea, where atheism has used police and military force to make itself felt.
Atheism peaked in popularity in the twentieth century, resulting in history's bloodiest wars (WWI and WWII) and several massive genocides. In the twenty-first century, atheism seems to be on a decline: as the results of research in various fields, from DNA to space-time physics, gradually makes itself felt, specialists in those fields see atheism as either unlikely or implausible.