Atheist sure put a lot of time, money and effort in denouncing a God they claim doesn't exist.
Why is that?
Why does something that's believed to be nonsense get these people so worked up?
These people are the epitome of cowardice IMO. They seem to only go after Christians. I've yet to see them challenge the Muslims on their beliefs.
First of all, not all atheists are anti-God. Most are what would be popularly labeled as agnostics.
A better term would be non-believers. What these people try to do is to get people to make decisions that are based on logic, reason, analysis, evidence, fact, and humantiarian morals.
Example: anti-LGBT laws are not based on any of the above but on primarily religious grounds. There are bigotted nonbelievers who would also discriminate against LGBT people but discrimination is immoral in a humanitarian sense. By encoding into law a religious conviction or discrimination one is oppressing those who do not share the same religious conviction or prejudice.
That's one reason, most likely the main reason, why nonbelievers spend money on anti-religious billboards.