even when the elected officials lower the taxes because their constituents want to have more money to spend on private religious schooling (and don't use the secular public schooling that would be fund through the taxes). The court's decision in Incantalupo v. Lawrence Union Free School Dist. (E.D.N.Y. Aug. 24, 2009), which so held, strikes me as entirely correct. In fact, as the court pointed out, a contrary decision would itself have violated the Religion Clauses:

Plaintiffs seek to deny Orthodox Jews [and presumably other religious groups that heavily use private schools -EV] political rights possessed by every other group in the United States: the right to mobilize in support of religiously neutral government policies, and then have those policies enacted through normal democratic processes. And Plaintiffs seek to do so because, Plaintiffs allege, the School Board's religiously neutral government actions are motivated by the Jewish faith, instead of anti-tax sentiment generally.

Plaintiffs thus ask this Court to discriminate against Orthodox Jews by finding that lower taxes and smaller government are unconstitutional because many of the tax cut's beneficiaries would choose to allocate their tax savings to Jewish education rather than secular pursuits. But if the First Amendment means anything, it is that the Government cannot prohibit individuals from spending their own money to fulfill the obligations of their religious faith. Thus, if lower taxes and school spending are not unconstitutional by themselves (and they most assuredly are not), these policies do not become unconstitutional simply because some taxpayers might spend their own money as they see fit, in support of their own preferred religious institutions.

For more, see this Religion Clause post.