Short answer: No, you can't add "be" there. Peace isn't a "position." Long answer: The whole sentence is awkwardly worded and doesn't make much sense. I would recommend that you find better learning materials.

Yes, another word should be susbtituted for peace, and the sentence is not great. That aside, it works fine as an addition, though it could change the shade of meaning. To "be" the position means that it is the *stance* people hold. The author may have meant something slightly different with the word position -- a place within a rank order.

Adding ‘be’ seems fine to me.

You can but the meaning will change