Sure, but if we keep working at it we'll reach a point of harmony...
Sure there is. Create a third class. The present breakdown of educational classifications needn't hold.
Oh, wait. There's that idealism again.
Yup, that's right, it's idealism again.
At some point, idealism needs to actually become pragmatic action. The reason I harp on about the 2015 science curriculum is it is a simple example of something with a hard deadline and a practical impact. 'Harmony', 'negotiation' and this concept of a 'third class' are all well and good, but in no way do they illustrate how your idealism would impact on reality, or actual decision impacting on the classroom.
I am completely in favour of harmony and negotiation. I'm also quite idealistic, and generally optimistic. However, I'll readily admit that you'll never reach consensus positions on everything. I am completely at a loss as to how you could think differently, to be honest.
To take an overly idealistic position whilst not being able to apply this to a practical situation means that your ideals will remain divorced from decisions being made. In effect, your decision becomes non-action. To effect action, you need to determine the best way of applying your idealistic viewpoint, which is (I would readily admit) very difficult and frustrating to do. In this particular case, if you believe inclusion of creationism to science curriculum can be catered for, whilst building harmony between all sides, I'd suggest you're mistaken.
If I'm misunderstanding you, on the other hand, more than happy to be clarified.