Because atheists fight for whats right, we purposefully dont follow religions because they are in control of your behavior.. Whether its right or wrong, they own you. We just do whats right despite what anyone else says lol.
And Iceland (I think) is 98% Atheist and they also have an extremely low crime rate. See a pattern? It's because WE do the right things because they're the right things to do, not because we fear retribution if we don't do the right thing. SO don't say we have no morals. I think we have more morals than most religious people, since we CHOOSE to be good, and religious people are coerced into it.
The image is commentary on how religion has lasted for so long. The joke being that you cant milk a cow for 2000 years but you can milk a story about morals and values and twist it to your own meaning it relevant to the picture