There are a few points I wish to make in hindsight of this meme albeit in brevity.
Firstly, I find myself in agreement with much of this meme, however, there is more to this than simply accusing the atheist of “irrational behaviour.” Let me explain.
Many atheists (particularly the New Atheists) are perhaps the most vitriolic minority of western people today (who tend to like hiding behind the anonymity of the internet). New Atheists are particularly repulsive for most people looking from the outside in, and this is certainly a reason why many other atheists distance themselves from the movement (see my article on atheist philosopher Massimo Pigliucci). It would also, however, be grossly unfair and insincere to accuse all atheists of being as vitriolic as the New Atheists as that would be far too much of a generalization. The obvious truth is that you get the good and the bad within the context of any worldview. Therefore, this meme is particularly targeting those atheists who possess the New Atheist mentality.
The meme is further a generalization as it assumes that all atheists spend their time “looking for forums where they can argue that God doesn’t exist.” Of course generalizations are to be expected from Christian propaganda (or any propaganda from any worldview), however, there is also truth to this. It would appear that many atheists do seemingly spend most of their lives & time, or as the meme calls it our “most valuable resource,” being overly present and extremely insolent online. As a result of this it appears that there is an intense emotional attachment to religious subjects on the part of many atheists. If there was no emotional attachment then there would, in most cases, be no need for the atheist to look, scour, search or hunt for online opportunities to ridicule and/or debate believers. However, most atheists will not admit this, yet this doggedness on the part of the internet atheist may also be why many Christians accuse atheism of being a “religion.” Of course I do not agree with this for the simple reason that atheism is not a religion. However, many atheists from the prophets Dawkins, Harris, Hitchens, as well as the evangelists (for instance, those who have spaghetti monsters for profile/cover photos on Facebook – yes, I have run into a fair share of them!) do indeed give atheism an overtly religious aura.
Nevertheless, there are constructive, rational and substantive reasons as for why atheists talk about God and/or religion on forums or via any other medium. For instance, it could be in relation to politics, personal belief, religious agendas, on-stage debates, religious fundamentalism etc. In this context it would not be irrational to talk about “something they claim doesn’t even exist,” just as it would not be “irrational” for me to debate a Muslim on his god whom I also don’t believe exists. I would further argue that the meme is correct in reference to time being the most valuable resource on an atheistic worldview. This is something that atheists are well aware of: that they have a limited amount of time in this world, whereas for Christians life goes on into eternity. In hindsight of this it would appear strange that many atheists do waste so much time focusing on things they do not believe in.
In conclusion I would classify this meme as Christian propaganda that does hold some truth, but yet is also not entirely truthful. It is possible to have purpose in debating and dialoguing about things that one does not believe exists, and it is also true that some atheists seem to give the impression that their worldview is a religion, although it really isn’t.