As is to be expected from the unintended irony in Christian memes, one has to wonder why they are happy posting a meme that admits childhood indoctrination is something atheists feel they have to unfetter themselves from in the first place? Are they suggesting that their own childhood indoctrination is something that has been fettered upon them?
That this is a painful experience says as much about the harm felt, as it does the harm inflicted.
The quote is somewhat curtailed, and usually includes the following,
“I do not share the crusading spirit of the professional atheist whose fervor is mostly due to a painful act of liberation from the fetters of religious indoctrination received in youth. I prefer an attitude of humility corresponding to the weakness of our intellectual understanding of nature and of our own being. [src]”
While I agree it shows a general disdain for professional atheism, it does nothing in and of itself to defend Christianity either. So its use in attempting to show a general disdain for professional atheism, belies an observation that the poster cares more about the denigration of, rather than a general disdain for, the professional atheist. Along with the fact that there are probably very few “professional” atheists – those that make a living from it – compared to their religious brethren, this meme appears as nothing more than a misplaced sleight on their interlocutors. That it also serves a purpose in denigrating their own stated position is just gravy.
At least, in posting this meme, they aren’t claiming Einstein was a theist.