While they do not fund the schools many states have allowed state funds to assist religious schools or students. For example, providing transportation to students who decide which schools they want to attend. Or, providing federal grants for construction projects for non-religious purposes. Or allowing religious schools to participate in scholarship programs available to other private schools.
"Chief Justice John G. Roberts Jr., writing for a conservative majority in the 5-to-4 ruling, said the Constitution’s protection of the free exercise of religion requires equal treatment for religious schools and parents who want to send their children to them.
“A state need not subsidize private education,” Roberts wrote. “But once a state decides to do so, it cannot disqualify some private schools solely because they are religious.”