A key ingredient in religion is faith. In fact, I would go so far as to say that if you don't have faith, you're not religious. There are two approaches to the discovery of truth. One is rational, the other is spiritual. The rational approach deals in observation, repeatability, testing, and empirical sampling of truth. Spirituality deals with introspection - it attempts to extract truth from emotion. Rationality never actually has to be tied directly to truth. In matters where we use rationality, we accept that truth is not known, but rather, approximated. Spirituality requires faith to tie it to truth, because it isn't an approximation of truth. Faith is the leap that ties your discoveries from your analysis of your emotions to truth. Without faith, spiritual introspection is useless for discovering anything but your own mental state.
Faith is by definition a belief in something irrational. Since faith is required for religion, and faith is inherently irrational, religion is inherently irrational.
I know this is a bit off topic, but while all that was very thoughtful, the bold part was questionable. This being the net and all, and not wanting to waste much time, this is what Dictionary.com has for the definition of irrational.
ir⋅ra⋅tion⋅al
   /ɪˈræʃənl/ Show Spelled Pronunciation [i-rash-uh-nl]
–adjective
1. without the faculty of reason; deprived of reason.
2. without or deprived of normal mental clarity or sound judgment.
3. not in accordance with reason; utterly illogical: irrational arguments.
4. not endowed with the faculty of reason: irrational animals.
I didn't think math definitions were needed here.
The issue is how you couch the term, because irrational has the connotation of "crazy" or "insane." Used gently, I could see it, possibly, but let's try this in another subject, Darwinian evolution. It's foundation is the hypothesis that all life sprang from lifeless primordial substances, and through constant accidental genetic improvements, evolved into ever more complex and capable forms until we finally arrived at Barack Obama and Scarlett Johansson. The problem with it is twofold.
- It defies known principles of science
- The evidence for it is almost entirely lacking
Primordial goo couldn't have produced anything of ever growing complexity, because the environment would have broken down anything resembling complex proteins or enzymes, never mind RNA or DNA. Your own body is constantly rotting and dying from within. It's corrosive to itself. The only thing that keeps it going and living is the fact that the body constantly repairs itself and cleans out the damage and decay. So in order for life to have evolved from non-living matter, you have to assume that the entire environment of the planet was constantly building, protecting, and even improving the molecular development of chemicals from non-organic to organic to living. In short, you have to assume that from the very beginning, the Earth itself was a living thing, and worked itself to produce life.
The fossil record also fails to support Darwinian evolution because it presents life in discreet stages, with no transitions between living things. There is no T Rex grandaddy you can place before T Rex, and a T Rex grandson after him. The nature of fossils found in the fossil record is the basis for the hypothesis of punctuated equillibrium, or "the hopeful monster." However, it requires some sort of drastic environmental changes to justify the sudden appearance of countless species, and the fossil record doesn't give any indication of that either.
Both hypotheses try to explain the world as best they can, and both come up quite a bit short. In essence, they both are forced to make leaps of faith, because the evidence is just lacking, to draw the conclusions they do.
I'm not sure "irrational" is the word either of us would use for these notions, although there are times I think scientists are crazy.
Such as the rabid spite from the scientific community heaped on so-called cold fusion, despite the fact that evidence indicates something unusual is going on that can't be explained from known electro-chemical reactions. And in fact, energy levels point to the possibility of some unknown atomic reactions taking place in some of them, with the release of weak amounts of radiation.
Having been a student of science for some years now, I can assure you that Science is it's own dogma, as entrenched and reactionary as anything you can point to in the Catholic Church of the Middle Ages. And yes, this I would call irrational. But I sincerely doubt that anyone has or will use that term to describe any scientific school of thought, because science is all about being logical and rational. At least that's what they say.
As for T Mars' post above, I wonder how much longer it will be until Obama sponsors a "Take a terrorist to lunch" initiative...
Edit: one more thing. I just watched the Glenn Becvk piece above. We need more Glenn Becks in this country, otherwise, the Obama maniacs are going to have their way, until the dollar spontaneously combusts from lack of value, and then we all go down.