Fortunately, you're mis-informed.
Atheism is quite old. There are tribes in Africa who developed no ritual/religious traditions (Will Durant has written at some length on them, if you're interested) who might be considered the first atheists. As far as traditional western skepticism/atheism, that developed in the 16th century and often overlapped with (or was disguised as) deism. Many of the so-called deists of the American enlightenment (including Benjamin Franklin, David Hume, and Adam Smith) were prone to visit the Salon meetings of Paul Baron d'Holbach, who was an early and vocal atheist intellectual.
Like most of the enlightenment, it was a review of greek philosphy. Protagoras wrote, "With regard to the gods I am unable to say either that they exist or do not exist," in the 5th century and Lucretius is probably the most famous epicurean atheist of the ancient greek tradition.
It is also widely suggested that Cicero (of Roman fame) was an atheist aswell, having penned to his friend "In this subject of the nature of the gods the first question is: do the gods exist or do they not? It is difficult, you will say, to deny that they exist. I would agree, if we were arguing the matter in a public assembly, but in a private discussion of this kind it is perfectly easy to do so."
And of course, it cannot be omitted that the developement of socialism came along side a dramatic growth of anti-theist fervor in europe and asia during the late 19th and early 20th century. It goes without saying that Marx, Engles, Lenin, and other political figures of that time were quite stridently atheist.
So the idea that Atheism is a recent development is completely without merit.
I didn't state Atheism was a recent development, I'm well aware on how long it existed. What I stated was the "Atheism movement" as in when mass peoples begun to flock towards the concept. Its similarity is that of one like the "women rights movement": people have been advocating women rights for a long period of time dating back to the formation of the United States of America and even Greece but only until the late 1900s did it become prominent (and established) as mass peoples began to flock to it in support.
I may be wrong, but never in history than today have I seen a mass movement/flocking of peoples towards Atheism.
Reactionary atheism does tend to aim at western religions more than eastern, but I think this has two root causes:
1. Most people in the west aren't familiar with hindu tradition or anything but Aberhamic religions.
2. Neither religion has attempted the ammount of push-back against science and reason as the Aberhamic traditions. In-fact it's quite possible to be a buddhist and an atheist (at least in some schools of buddhism).
That is true, but as atheism is literally "without god/deity" I would like for it to transcend other than targeting Catholicism or any of its branches.
Few polls dispute this handily. The US Religious Knowledge Survey, released in 2010 from the Pew Forum on Religion & Public Life, found atheists and agnostics know more basic facts about the Bible than either Protestants or Catholics. That isn't to say more of them has read the bible cover to cover, but apparently they're more knowledgable.
"Atheists and agnostics, Jews and Mormons are among the highest-scoring groups in a 32-question survey of religious knowledge by the Pew Forum on Religion and Public Life. On average, Americans got 16 of the 32 questions correct. Atheists and agnostics got an average of 20.9 correct answers. Jews (20.5) and Mormons (20.3). Protestants got 16 correct answers on average, while Catholics got 14.7 questions right."
That's what typically happens when the majority of an entire movement target only a specific religion and its related cousins. Then you have to also take into account about the Catholic/Christian mission to spread influence worldwide, there's bound to be more religious followers unknown to basic facts than there are Atheists/Agnostics to the sheer size of today's population of religious followers. Either way, the poll results are expected given on what we have today.
But I'll take into account my perception of the amount of knowledgeable Atheists/Agnostics were wrong.