(Note that I've sourced a bunch of the stuff here, but it's getting late and trying to source all of it is becoming too tedious. If you don't believe what I'm writing, look it up for yourself. Also, though I take some digs at Christians, those are primarily aimed at Christians who are using lies to spread their beliefs.)
First, some people tried forcing our children to learn creationism in lieu of evolution. Because that's clearly a religious belief, our courts threw that out.
Then, some people tried forcing our children to learn "creation science" alongside evolution. Because that's clearly a religious belief, our courts threw that out. (Hint: if it has the word "science" in the name, it probably isn't).
Now these people are trying to force our children to learn "intelligent design". They keep trying to force their religious beliefs on others. The courts keep shutting them down, but since they have no respect for the First Amendment of the US Constitution, they don't care. They're sitting in court lying their asses off as if somehow God won't mind deceipt in his name.
Their first assault on science lies in claiming that evolution is "just a theory". There are plenty of flaws with ID, but let's start with the "just a theory" part. What the Christians pushing "intelligent design" (ID) want us to think is that "theory" more or less means "guess". It doesn't.
A theory, in this context, is set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.
In other words, we can say "theory" when scientists identify some phenomena in the natural world and and have a generally accepted way of explaining it. This isn't to say that they believe their knowledge to be complete or infallible. It says that scientists are reasonably convinced that they have the basic knowledge correct. For example, you never hear the ID folks attacking the germ theory of disease. Also, few researchers deny the theory of global warming. The dispute there is over the causes of global warming.
Of course, the Christians like to point out that it used to be believed that the Earth was the center of the universe (and Christians put Gallileo under house arrest for the rest of his life for learning the truth), that the world was flat (this belief wasn't as widespread as is commonly believed), Newtonian physics could explain the workings of the universe (Einstein delivered the killing stroke on that one) and many other "theories" have since been disproven. But that's the beauty of science. We make mistakes, we learn from them and we move on. The ID folks, on the other hand, rather than presenting a compelling case that evolutionary theory is wrong, simply assert that it is. The "bad science" they like to point to are typically theories which have been overturned by compelling cases. Scientists are humans and they often don't like to admit they're wrong, but sooner or later, the truth wins out and new theories are born. These new theories explain what we observe around us.
The word the Christians are actually looking for is hypothesis. A hypothesis is a tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation. A hypothesis doesn't necessarily explain what we observe around us. It's an educated guess which might explain what we observe and, if it does, it might become a new theory. In the scientific world, a hypothesis has much less importance than a theory, but there are few credible scientists involved in evolution research who would call evolution a "hypothesis". Thus, the Christians can't really be honest about what they're saying so they're take advantage of the fact that most folks don't really know what a scientific theory is.
However, we can back up for a moment. Since evolution is a theory, it follows that scientists don't dispute that evolution is occurring. Is there any controversy here in the scientific world? Of course there is! There's all sorts of debate about niggling aspects of the theory but the well-established fact of evolution itself could not be tossed out without tossing out much of the work of geology, paleontology, zoology, botany, comparative anatomy, molecular biology, population studies, genetics, biogeography and so on (list thoughtfully stolen from the book "Science Friction"). In fact, the ID folks don't quite say that evolution doesn't happen; there's too much evidence that it does. Instead, they claim that it's "guided" or "instigated" by an intelligence. Life, they claim, is too complicated and shows too much evidence of design (such as our appendix or poorly designed eyes, I suppose) for there to have not been an intelligence behind it. In other words, they're trying to present an alternate hypothesis to justify the theory of evolution. There are, however, some problems.
For a hyphothesis to be validated, it must be falsifiable and testable. It's also helpful if it makes predictions. Current evolution theories fit these criteria (don't bug me about it, read the literature if you doubt it. Those who claim that these criteria aren't met are saying "I really don't know anything about evolution"). ID does not fit these criteria. It's not falsifiable because it's not possible to construct a counter example in which ID can't slip into a gap. It's not testable because the ID people themselves say the "intelligence" is beyond the purview of science. It doesn't make predictions for the previous two reasons.
But what is that intelligence?
Ah, that's where they get stuck. It's a "no fault" eviction.
In the state of Oregon we used to have a law (perhaps we still do) which stated that a tenant could receive a "no fault" eviction from a landlord and have 30 days to vacate the premises. No reason has to be cited -- nor could it be. If the tenant challenged the eviction and the landlord showed up in court and accidentally confessed that other tenants were complaining about the noise, it would no longer a "no fault" eviction and the eviction order would be vacated. The landlord has to keep his mouth shut.
If the ID folks admit in court that the "intelligence" is God, ID will get tossed out at as the unconstitutional violation of separation of church and state which it clearly is. (You can also check out intelligentdesign.org. They have many references to "creationism", thus being one of many ID web sites betraying their origins). If you paid attention to the recent court case about this, you'd discover that the folks supporting ID would repeatedly assert that since ID is a science, they really can't comment on the nature of the guiding intelligence. Really? Why the hell not? Don't they have theories? There's nothing in science which says you can't speculate. After all, where do you think hypotheses come from? Are they spontaneously generated? No, they're not, but if they ID folks do what scientists do and question everything, they might make the mistake of being honest about what they think ID is and they'll get evicted from the class rooms.
In reality, if you read the ID literature, there's a fair amount of debate about precisely when the intelligence kicks in. Some think He, ahem, some vague intelligence, started it all and sat back. Others claim that the vague intelligence steps in every once in a while when things need to get done. They're really not sure. It's like listening to kids argue whether Batman or Spiderman is stronger. The major thread they've seized on is when scientists disagree about an aspect of evolutionary theory or if there's something scientists can't explain, there must be the vague intelligence involved. This "knowledge from ignorance" approach is better known as the God of the Gaps argument which can be summed up as "I don't know the answer so it must be God".
Instead of searching for truth, they hide or obscure it. They like to talk about the weak anthropic principle but they don't like to talk about multiverse hypotheses which would negate the need for an intelligence. They cite bacterial flagellum and eyes as examples of "irreducible complexity" despite fairly clear evidence of the reducibility of each -- thus they prey on our scientific illiteracy. Perhaps the worst, though, is that they claim to be honest scientists when what they're really doing is lying in God's name.
Of course, there are still those who are attracted to alternative explanations because they mistrust science. Here's a reality check kids: science is not bad or evil. People are often bad or evil but science isn't. Science does not want to be anthropomorphized. Science isn't threatening your God because as the late Pope John Paul pointed out in his defense of evolution, truth cannot contradict truth.