I demand you return those goalposts at once!

PZ Myers continues to field creationists’ demands for debate with scientists:

Carl Wieland, the creationist clown from Australia, wrote a bitter article denouncing atheists and scientists for refusing to give him a platform to yodel nonsense on, and one of the things he did was link to my my public refusal to debate him. Unfortunately, what that meant is that all of his Too-Stupid-To-Know-They’re-Stupid acolytes came charging over to declare that creationism was too scientific, evolutionism is a religion, scientists are afraid to debate their pet idiots, you’re all mean poopyheads who call us names, yadda yadda yadda. It’s turned into a regular storm of argument that has filled up the thread with over 1100 comments.

I don’t have much to add to the discussion of whether scientists should debate creationists. I’m just going to indulge in a tangent off Prof. Myers’s paraphrasing of creationist assertions that creationism is too scientific and that evolutionism is a religion.

Specifically, I want to talk about the claim of evolutionary theory as religion.

My question–and I’ve been wondering about this for some time–is, what is that supposed to mean, “evolutionism is a religion”? Is religion supposed to be a good thing, or is it not?

Why is it that “religion” means a belief or idea is sacred, moral and exempt from criticism, if it involves going to a place called a church (or any recognized house of worship) to worship God, but, when the “religion” in question takes place in a laboratory and examines evidence, then “religion” means it has no truth value and can be dismissed without evidence?

Why is it that we’re horrible, shrill, strident, intolerant people for examining the religion of a person who believes the Earth is roughly 6,000 years old, but evolutionary theory (or biology, or science in general) is “just a religion” as if it’s no more valid than anyone else’s opinion?

In fact, here’s another question that’s been bugging me for some time now:

What exactly is the definition of a religion?

Seriously; I haven’t yet seen a thorough answer on this. The closest thing I’ve seen was from Daniel Dennett in Breaking the Spell, which he devised for the purposes of his book about the natural origins of theistic faith, but not for everyone’s purposes.

When we talk about religion, most people use it interchangeably with faith. Otherwise they take all the systems now accepted as religions and reverse-engineer a definition out of what all those entities have in common. Often they simply take most of the major world religions, reverse-engineer a definition out of those, and then find excuses to exclude the ones that don’t fit. It is all well and fine to say that Buddhism isn’t really a religion because it doesn’t worship any gods, but then: why must all religions worship gods? Where does the definition of religion begin? Buddhists say it’s a religion, and on what grounds does anyone get to say they’re wrong?

Actually, religion is more like gender: everyone talks about it as if everyone else already knows what it means. We assume everyone knows what we’re talking about because it’s around us all the time. The result is that, between believers who say religion is what brings comfort to their lives and makes morality and justice possible, and freethinkers who say religion is irrational and divisive and makes oppression and bigotry possible, we don’t really know what makes a religion in the first place. What do you need to have in front of you before you can call it a religion? When something is already called a religion, what makes it qualify for the word? Again: where does the definition begin?

All that said, if someone can answer my question, it probably still won’t explain what binds together the inviolate religion characterized by faith, and the mere religion based on science.