James Madison, in the veto message quoted above, certainly seems to have felt that taxpayer money should not support religious institutions. Do you disagree with him?
When "support" really approaches "establish", naturally it should be disallowed. When funds are used for partially secular purposes, it should be allowed.
"Partially secular purposes?" That's a loophole you could drive a proverbial truck through. Would Madison have allowed the donation of land for a church if they had promised to allow the city council to meet there? If they had promised to feed the poor? I don't think that either of those partially secular purposes would have swayed him. Note that he objects to even the use of taxpayer funds by a religious society.
It would clearly be a judgement call what level of support constitutes establishment. The present-day interpretation does not use a Madisonion test, and it would be ludicrous to institute one now given circumstances beyond the control of we First Amendment interpreters.
I guess SCOTUS would have to construct a conventional test narrower than a truck.