In response to the cases you listed, I could just as easily say, "Don't you believe there is a constitutional right to abortion? Haven't you heard of Roe vs. Wade?" It really comes down to one's philosophical standpoint on the constitution. Many poor rulings, including those you mentioned, have come from people who see the constitution as a "living document" and therefore something that is subject to the whim of the majority at any given time. It's quite clear that the founding fathers would not have considered it to be unconstitutional when a teacher says, "Some people think science cannot explain things completely and have written [insert book title here]. You can read it on your own time. Now, back to evolution." But apparently you think that sentence is unconstitutional. That's quite a stretch. And yes, within my hypothetical teacher's statement I am implicitly acknowledging that ID is not science. I believe that is safe to say--however, it does have some value in showing the limits of science. Therefore, it is worth two sentences in a science course.
But allow me to answer the other question as well: Yes, it should be unconstitutional. If you want to make it optional for students to receive religious instruction, fine. But the minute you make it a mandatory item in a mandatory class you have infringed on my right to freely practice religion as I see fit. And before you get into the semantics of whether the exact wording of the Constitution extends to schools, keep in mind that this answer is based on what I think it should be, not necessarily how it could be interpreted. It just so happens that the current interpretation of the Supreme Court matches mine and not yours, but that is irrelevant to my own desires. My view would be the same even if the rulings were not in my favor, because I believe the Constitution intended, in cases where rights conflict, to favor the rights of those being imposed upon and not those who are doing the imposing. In other words, you have the right to swing your fist around, but your right to do so ends where my nose begins.
I asked my question to learn if you have the courage to honestly answer. I had no intention of beating you over the head with your answer, and was not trying to ridicule you specifically or Christianity in general with it. I simply wanted to learn the measure of your character by seeing if you were honest enough to acknowledge that there is at least the perception that false witness was being perpetrated in the name of religion. That you dodged the question pretty much told me what I was seeking, so there is no longer a need to answer.