Governments have used vouchers to spend billions of dollars on private education; much of this spending has gone to religiously-affiliated schools. ... We use a dataset of Catholic-parish finances from Milwaukee... We show that vouchers are now a dominant source of funding for many churches; parishes in our sample running voucher-accepting schools get more revenue from vouchers than from worshipers. We also find that voucher expansion prevents church closures and mergers. Despite these results, we fail to find evidence that vouchers promote religious behavior: voucher expansion causes significant declines in church donations and church spending on non-educational religious purposes. The meteoric growth of vouchers appears to offer financial stability for congregations while at the same time diminishing their religious activities.
--Daniel Hungerman, Kevin Rinz, and Jay Frymark, "Beyond the Classroom: The Implications of School Vouchers for Church Finances," on where your treasure is, there will your heart be also