Virally all spending by government is unconstitutional. This is one of the most flagrant examples. Taking money from people (taxation) to pay for spending that violates people’s consciences is sufficient reason to end the funding or make it voluntary Government schools, known as public schools, is the best example of the improper use of taxpayer dollars. Schools, no matter how they are structured, should be funded by fees, scholarships, private grants, donations. etc.
Source: Landmark Ruling Halts Unconstitutional Taxpayer Funding of NJ Yeshiva and Seminary