It's easy to sympathize with programs that try to help poor kids get a decent education in the worst neighborhoods and school districts in the nation, and many parochial schools in the inner cities are doing a heroic job of it. But let's not lose track of what parochial school education is all about: It combines reading, writing, and arithmetic with systematic indoctrination of students in the tenets and practices of religious faith. The establishment clause undoubtedly means that government cannot make any of us pay tithes or taxes to any church. So why do you think it allows government to make us pay taxes to be used for religious indoctrination in faiths we may not share?
You say that the public support for religious teaching is "indirect" in a voucher program because it "flows to religious institutions only as a result of the independent choices of private people." But surely the issue of public support for religion doesn't disappear merely because the money has been laundered through families' checkbooks. The economic reality is that voucher programs such as Milwaukee's transfer significant sums of taxpayer money to parochial schools--in Milwaukee, up to $5,000 per child--without any requirement that those funds be earmarked or segregated for nonreligious use.
You also say that the voucher program is "neutral" because it benefits private nonparochial as well as parochial schools. You seem to assume any government program is fine so long as it treats religious entities the same way that it treats other entities. But the establishment clause, if it means anything, means that sometimes we have to treat religion differently. For example, we might want to have a National Endowment for Prayer just as we have a National Endowment for the Arts or a National Endowment for the Humanities, but the establishment clause would surely bar a prayer endowment even if it were just one more cultural endowment thrown into the mix.
Leaving religious schools to flourish on their own, with private funds raised from those who share the faith, hardly amounts, as you say, to "hostility toward religion." Religious exercise is alive and well in this country, and government of course cannot penalize the practice or teaching of religion in any way. But you seem to think that the same principle entitles religionists to an equal share of any subsidy the government gives out. I don't see why you think a decision to withhold a subsidy amounts to "hostility." By your argument, pro-choice folks should count the Hyde Amendment, which provides that Medicaid may be used for childbirth but not abortion, as "hostility" toward abortion, rather than merely the "nonsubsidy" of abortion that the Supreme Court held it to be.
I wouldn't stop the firetrucks from racing to the aid of a burning church, nor would I stop the police from arresting the thief who is running away with the contents of the church poor box. But extending to religious corporations or citizens the same protections of the public order we extend to all does not mean we should be forced to finance preaching and proselytizing as well. And in the school setting, teaching and preaching are inseparably intertwined.
So, Michael, it seems far from certain that the Supreme Court will uphold voucher programs such as Milwaukee's when the establishment clause challenge finally gets there.
Every best wish for the holidays,