I'm going to take it as a premise that rationality is better than ignorant bliss.
While there's pleasure to be had in appreciation of the natural world and the human beings in it, the religious strongly believe that they have the huge share of "bliss" based on those tingly, orgasmic feelings they get from parts of their beliefs. Based on happiness alone, I consider it self-evident that we can not defeat religion - especially the fundamentalist varieties - by convincing people that atheism will make them happier.
That's not to say I'm not happier as an atheist, but rather that the joy of it is a useless basis on which to encourage others to leave their irrationality behind.
I'm writing this because of the tactics I see many atheists using. Insults and degradation get us nowhere. Trust me, I've tried. When I was new to atheism, I was angry at my former beliefs and rejected them and all who espoused them with vitriol and fury. It never impressed anyone.
Patience and rationality, however, can be convincing if they are consistently used. Let the religious rail, calling us fools. Let the religious advocate gruesome treatments of other religious people. Let the religious froth at the mouth. Let them knock on doors and be the proselytizers. This is not our place and not our tactic.
As atheists, we are best to be calm. We advocate freedom of and from religion. We must never attempt to limit someone else's beliefs - only their ability to force them on the unwilling. We will tell the truth, calmly, over and over again until people start to listen. It's the long, hard path, indeed, but the only time I've ever been credited with helping someone (#1172 if it matters) shake off religion is from that kind of behaviour.
Cruelty and mockery will only ever benefit the religious, as they already have a nice, safe rationalization that says that atheists are angry, miserable, hateful people. We have to show them differently.
As I'm watching the powerful people in this world use religion to get people to kill each other, Crusader against Jihadi against fundamental Zionist* against ... I don't even know the word for a crusading Hindu or Sikh ... I'm convinced that we won't be safe until we get society to shake off the shackles and blinders of religion and embrace rationality.
Does atheism proof a society against despotism? Of course not. Atheists are still human beings and can therefore be just as immoral as anyone else. Atheism does, however, deprive leaders of the religious excuse for immorality. It deprives them of a ready handle to grab which lets them declare immoral acts to be righteous and cruelty to be acceptable behaviour. If atheism is enforced, as in Stalinist Russia or present day China, it can be just as bad as enforcing religion. It is important, therefore, to let people believe what they will and convince them without suppression to follow the path of logic.
No, it's not an easy road, but it's the best, healthiest path for our society to take and we have an obligation, as humans to other humans, to do our best to shepherd it along.
* - this seems to be a vague term. I refer here to those people supporting, among other things, the building of Jewish-only settlements outside of the U.N. recognized borders of Israel.