I'm definitely a passionate atheist, and may or may not be called "evangelical" or some such behind my back, but I really can sympathise with your sentiment. Though, it does beg a deeper understanding of where the more vocal atheists are coming from.
A quotation from Kurt Wise may sum up the type of thinking that most atheists are fighting against:
...if all the evidence in the universe turns against creationism, I would be the first to admit it, but I would still be a creationist because that is what the Word of God seems to indicate. Here I must stand.
This is the kind of inflexible commitment to superstition that flies in the face of reason, intellect and, above all, evidence. It's nothing short of an insult to the human intellect, yet sadly it is a very common stance among religious fundamentalists of all kinds. If "tolerance" means sitting back and allowing this ignorance to be advanced, then perhaps this concept of tolerance should not be tolerated, for to be tolerant would be to tolerate the worst kind of ignorance... the willful kind.
To illustrate an atheist point of view, on the other hand, I'll quote Dawkins (who is quotable and oft quoted not because of some misguided personality cult, as some believe, but because he describes both atheism and its arguments honestly and succinctly):
If all the evidence in the universe turned in favour of creationism, I would be the first to admit it, and I would immediately change my mind. As things stand, however, all available evidence (and there is a vast amount of it) favours evolution. It is for this reason and this reason alone that I argue for evolution with a passion that matches the passion of those who argue against it. My passion is based on evidence. Theirs, flying in the face of evidence as it does, is truly fundamentalist.
Though the creation/evolution issue is but one of many talking points on the atheist roster, it is a quote which does put into perspective where the so-called "new atheists" tend to come from. A passionate, but flexible and evidence based reaction to the inflexible ignorance which seems to be the requirement of religious thought, and which ultimately - invariably - leads to further injustices and social ills.
This comment probably seems like holier-than-thou soapboxing - and maybe it is - but it's as sincere a description of vocal atheist motivation as I can manage, and hopefully goes some way towards explaining why "evangelical atheist" is contradictory term.