I think you know more about science than the Constitution. How is allowing mention of ID establishing a religion by Congress?
It's God-Centric. Now, teaching God-Centric concepts in school may not seem like the establishment of a religion to you, nor even to me, but that's the part we're not entitled to quibble about: the Supreme Court has already ruled explicitly on that, and they say it is. Creationism is banished from the schools.
I myself want ID out of the schools not because it's religion--prayer in school is fine with me--but because it isn't science. But that's just me.