Beast Rabban, you seem to have misunderstood a few of my comments, so most of my responses will be clarifications.
Firstly, yes, I understand that there is a separation of church and state in the Constitution. However, the interpretation given to this is that the Founding Fathers wanted 'freedom of religion', rather than 'freedom from religion'
I've never seen a document from any of the founding fathers that suggested that. If you know of one, please let me know. There's quite a lot of evidence that some of them were specifically not the god-fearing Christians today's moral-reformers make them out to be. For example, from the Treaty of Tripoli that John Adams signed into law: “[T]he Government of the United States of America is not in any sense founded on the Christian religion...” And certainly Jefferson would have accepted "freedom from religion" as a legitimate interpretation: “The legitimate powers of government extend to such acts only as are injurious to others. But it does me no injury for my neighbor to say there are twenty gods or no God.”
It might, therefore, be beneficial to non-Christian children to learn the basic tenets of Christianity in order for them to understand, and not be excluded from, the common culture of their nation.
I'd agree with that more strongly than you might imagine. However, prayer in school is not an effective pedagogical means of doing that. Neither is direct religious instruction. Historical, literary, psychological, and anthropological methods would suit better in an educational setting.
Then there is the question of what constitutes 'meaningful instruction'. As a Christian, I'd strongly argue that religious education does constitute exactly this.
I assumed that - like in every school I attended or taught in - when a portion of the students are excused to participate in some religious study or activity, those left behind are give worksheets or other busywork that are not only contraindicated by many studies on effective practices but aren't even graded, since most of the class is out of the room at the time. Effectively, while some students are singing about Jesus, the other portion are learning nothing.
You mention in connection with history lessons on comparative religion teaching facts, rather than opinions or guesses. Presumably you mean that in their approach to religion, an atheist, philosophical physicalist approach be made to religion, rather than a religious interpretation. This is, however, merely another opinion or guess.
I'm not entirely sure what your accusing me of here, but by facts I mean things like "this is was X believe, this is what X do" with a focus on the real and meaningful divisions and issues within each religion (e.g., not teaching Islam as "normal Moslems versus terrorists" but from the more important division between Sunni and Shi'ite). I've seen people of a Christian background pay lipservice to religious diversity without ever making an effort to understand how religion functions in other cultures. To avoid that, I think a thematic rather than geographic approach to units would do much better (e.g., a unit on religious revelation, another on religious responses to modern biology or physics, another on how religions adapt to changing social contexts). The comparative aspect would come across much better that way.
Also, historians will tell you that history isn't about facts, but argument and interpretation, and the histories of different events and periods can vary widely, all based on the same basic facts.
Yes, and a good history class presents the different viewpoints held by historians and lets students come to their own conclusions - conclusions that should be drawn from evidence, not simply religious insight.
History is only one aspect of what I'd want the class to cover anyway. Social psychology and cognitive science should have nearly equal roles.
Regarding the teaching of religious history, this might actually strengthen religion, particularly in the field of science.
Yes, perhaps. Remember though, that its only recently that anyone in US society has even been able to say that they are atheists freely and publicly without suspicion, and even then we had the brief setback in the 1940s-50s when all atheists were presumed to be communists. There was even a tradition among deists in claiming that atheism was a logical impossiblity. That Christians have been and are involved in European science is expected in such a climate.
I wonder whether the relationship between religion and science would do better in a history class or science class. I have a feeling that a history class would neglect to show things like how even great mind's like Newton have historically used religion - the existence of god in particular - as a filler for the gaps that the contemporary theories failed to explain. These explanations - though common - are routinely dismissed as not being scientific, since they make no empirical claims. Just like ID is being dismissed today by mainstream biology.