does religious freedom necessarily mandate the strictest separation of church and state?
It seems that at first glance the answer should be a natural and automatic "yes," but then we face situations where it benefits the public good for the government to say, cooperate with religious charitable organisations, or offer financial aid for students of faith-associated schools, or provide public subsidies for restoring the exterior of an old but still-functioning cathedral.
The utilitarian in me has always been annoyed by arguments made by people I shall call fundamentalists of the secularist (atheist?) kind, who seem to assert that religious entities and religious interests should be treated as pariahs and outcasts who must not be touched by the state, indeed taking the idea behind the word "separation" to its most literal extreme.
So pardon me if I may declare something shocking: perhaps this separation isn't necessary in the first place.
Freedom of religion, and separation of church and state are quite two different things. Popular sentiments in the 18th century led a Convention to fashion an amendment prohibiting any law "respecting establishment of religion," but these are only related, not entailed by the premises that argue against laws prohibiting the free exercise of religion (or having no religion at all). Let us be reminded that the same popular sentiments also caused the massacre of a myriad of religious individuals in France, from all tiers of the religious hierarchy, in a particular period near the close of the 18th century -- and they were individuals who did not necessarily have a hand in the excesses of the Estate in which they were a member.
Religion, we note, is the only trait safeguarded from discrimination that is characteristic of changeable behaviour. In contrast it is not in one's easy willpower to change one's sex (and if science actually confirms this beyond reasonable doubt, orientation), race/ethnicity, nation of birth, nationality in general, handicaps and all that jazz that is generally taken to be protected. So please do not stone me if I question, "Why should religion fall into this category?"
For example, it strikes some of us as laughable (I should hope so) that political affiliation should be protected from discrimination, because this is already covered by the principles safeguarding freedom of speech, and by extension, freedom of thought, and the parts that are not covered should not be covered in the first place. The State has no right to force someone to be a populist, or for that matter, not to be one, but employers should have every right to fire someone for subscribing to crackpot ideas. If the ideas are irrelevant to the job, there are other forms of redress, such as the fact that the employer hurt himself economically for no reason, gathering the fury of peers and superiors and watchdog groups, but I digress.
It strikes me that freedom of religion falls along the same lines. People should not be able to vote on whether to forcibly convert everyone to a single religion, or make them atheist, or make them choose between a limited array of religions, and so forth, but this is just like people cannot vote on whether to make everyone a PAP member, subscribe to libertarianism, or force everyone to stop speaking Singlish. For such actions would be prohibited by principles covering the freedoms of speech and thought.
Nevertheless, these freedoms do not prevent us from ridiculing each other's speech, or each other's religions. But if governments are allowed to promote the interests of certain ideas of thought (along with their special interest groups, which are not necessarily against all freedom if the voters continue to tolerate those who allocate resources to them), or even certain ways of speaking, be it through public campaigns (Speak Good English Movement anyone?) or promoting secondary and tertiary-level forensics/debate, fiscal philosophies and ideologies, ideologies and philosophies in general, why should religion be excepted? Governments are allowed to make market corrections (how much they should correct, is of course a matter of dispute) and subsidise private economic entities, depending on the amount of public good they generate for society. Why should religious organisations be excepted?
No one's religious freedom is violated if governments choose to allow school vouchers to be used for faith schools, if that faith school generates the public good (via private economic transaction) the school voucher was meant to subsidise, and we can count financial aid in general as well. "But no!" go the militant atheists/secularists. "Anyone or anything religious must be a pariah! The state must not touch them!" The question of whether or not religious organisations should receive government aid is of the same nature as whether corn-based ethanol production should be subsidised by the US government -- a question ultimately decided by voters at the polls, based on the weighings of the costs and benefits and economic sense. Why shouldn't candidate X run on a religious ticket? Never mind that the official state policy is now said to be divinely-inspired -- unless the freedom of speech and thought (the ones that automatically cover freedom of religion) are violated, let the voters decide whether the policy benefits them.
The separation of church and state is necessarily entailed by religious freedom, for the reason that the two ideas sprung out of the same historical period, and their principles proclaimed at a common time. Taking the idea to its most logical conclusion, we can conclude that this same reason also justifies the rightful "cleansing" of the clergy in France. Ah, the First Republic -- the epitome of the most perfect separation of church and state -- the emblem of religious freedom!
Why, ignore anyone who says that these two ideas were separate solutions to the excesses of a religious establishment that had attracted mass resentment everywhere, or that in the United States, it might well have been a political compromise to prevent tearing the young nation apart along its religious, free/slave and socioeconomic seams. For it is known in a later historical case that because the abolishment (and ensuing execution) of the Russian monarchy came around at the same time that private property rights were abolished in Russia, where both policies were reactions against unjust socioeconomic conditions, and that because abolishing the monarchy is always a just action, we can conclude that abolishing private property is always a just action. From this well-known implication we can also conclude that because freedom of religion is always just, the separation of church and state is always just.