It’s not appropriate for an elementary school kids. Per the article, this applies to grades 5 through 12. So what, 1 year of elementary with the primary focus of impact on junior high and high school?
But if you are getting into questions of “what was more important to our founding fathers, rome or christianity?” I’d say that’s pretty difficult to separate because of thinkers like Thomas Aquinas that married Greek Philosophy with Christianity. When you begin with a point that God is the source of reason, and build off of that, I think you can’t easily separate that out.