1. Because something taught as fact for 40 years doesn't make it so.
2. People don't like to be criticized, especially when the real heart of the discussion is a class struggle of sorts, one world view trying to silence another world view.
3. Which is more important? To learn or do science or argue about mythology?
4. Science and theology have the same possibilities of corruption. Most of these complaints are human in nature rather than exclusive to either of the opposing paradigms.
Evolution Chamber was inspired by the Prometheus & Bob clip of the same title which I posted in another thread in promise of this one. For me, knowing there are so many science minded atheists who don't want to discuss religion I often throw a proverbial bone, allowing them, at least the opportunity to take or defend criticisms and open the opportunity for them to do what I'm asking you to do.
Teach me and present your subject as honestly and fairly as I have my own.
OK, I'll leave the Evolution Chamber bit aside, as I don't understand the references.
I struggle a bit to see a coherent issue in the 4 items on your list. So I suppose I shall have to treat each of the four individually.
Re yr (1), yes of course, when there is deliberate deception, plainly something can end up being taught as fact and turn out later to be untrue. Russian schoolchildren were taught for years that a Russian invented television for instance. Or take the forged Donation of Constantine. But I'm not sure anyone can deduce anything fundamental from such cases.
Re yr (2), You will need to explain how the Piltdown Man hoax illustrates that people don't like to be criticised or how it illustrates a "class struggle" of some sort. I don't follow either at the moment.
Re yr (3), how does the Piltdown Man hoax relate to your question? I can't see a connection.
Re yr (4), this has more substance to it than your 1-3, I think. I presume the point of citing the Piltdown Man hoax in this context is to show an example of corruption in science - which is fair enough.
Indeed, you can have corruption - or simply error- in theology and in science and I agree entirely that both can occur as a result of human frailty. What defences does each discipline have against error?
There is a self-correcting feature of science, which is that the theories of science are always judged by testing against observation. Sooner or later a dud theory will come to grief because observations will be found that contradict it. In the Piltdown Man hoax, it was found that an
observation was a dud. This process is a less often publicised but valuable feature of the way science works, too. People look at outliers, challenge them and repeat them to see if they really don't fit or if there is some artifact of the observation that it is responsible. (This happened recently with the Italian data that seemed to suggest particles travelling at superluminal speeds. It was challenged and found to be due to an artifact.)
In theology, it is less clear cut. I like to think that in the Western world there is sufficient freedom of expression and interchange of ideas that poorly argued theology will be criticised and eventually discarded. But as there are rival theologies that are intrinsically opposed to one another, and no means of objective arbitration analogous to the recourse to observation that science uses, it seems hard to decide who is right and who is in error.