The problem is that you keep saying that TE/EC is “creationism”, and it isn’t – as that term has normally been used in the discourse of the past 100 years in the USA. Nor does the NCSE call any of its Christian members “creationists.” If it did, it would alienate them and they would leave. Eugenie Scott was far too smart politically to do that. She knew that without substantial Christian participation (i.e., TE/EC participation), the NCSE would be seen as a political front for atheism and materialism. So she cultivated good relationships with TE/ECs.
I have no more time to spend on this. Read about Scott and Miller. You will see that I am correct.
Because of Dover legal decision, creationism being religion and not science is now law and precedence. Before Dover, TE/EC was being taught in most Progressive schools across the country. Why? Because a preponderance of Science Teachers and administrator were Christians and Catholics. Dover woke up the Catholics and the Mainline Christians and the Nones to the danger of letting the “camels nose in the tent.” So after Dover, there are watchdogs like FFRF who will go after seemingly minor infractions like we saw yesterday. TE/EC Christians and Catholic have a lot to blame on the present environment on DI and the ID wedge document.
To answer your question Patrick about why there are multiple churches I can think of at least one reason. Different denominations are sometimes at different levels. One might teach first grade teachings, another second grade teachings, etc. It doesn’t mean they’re necessarily preaching something false. They may just continuously teach the basics and someone might look for a deeper teaching at a different church. Another reason might be differences in interpretation of the Bible without changing core doctrines. For example there are reasons people use for believing both YEC and OEC. Whichever one you choose it doesn’t change Christianity. Sadly this causes unnecessary division in the church. Even nondenominational has become a denomination. Separation is sometimes unnecessary.