Maybe the antheism is more like the militant, proselytising atheism?
As for me personally, I'm happy to let everyone believe what they want - or not - as long as it doesn't harm anyone.
What does get on my nerves, however, is when people are pushing an antireligious discourse by twisting around history, and just perpetuating things that are, at best, misrepresentations, at worst, total fabrications. Religion, and all religions, have their bad sides - as bad as the people that make up a religion can get - but there's also good to be found.
When it comes to prayer, what is worse: telling someone in pain their beliefs are wrong, and their prayers useless, or letting them have this one source of comfort?
Sure, there are those who will go to another extreme, and refuse medical treatment, but let's face it, discounting their beliefs is not going to make them any more cooperative. Quite the contrary, in fact.