The specific religious test outlawed by that clause was the one in Pennsylvania that REQUIRED you to be a Quaker to run for office.
Yes, the Quakers were still denying others the right to hold public office right down to 1790, and at that time the NO RELIGIOUS TEST standard was for federal offices only.
No judge needed to determine the validity of Quakerism as a true religion or a false religion. Prohibition of that test was sufficient to eliminate the problem.
Judges, to be equinanimous, must be totally neutral, and even determining if one element of belief or declaration is truly religions is beyond their authority.
The courts have no jurisdiction on how communion is administered nor if the cup is made of gold or silver, or wood. No judge in our system can dictate the number of candles to be lit in a Buddhist temple either on the basis of 79 being truly religious and 80 being a work of demons.
I do believe we still have people who think it's within the jurisdiction of our courts to determine the validity of religious beliefs.
They are wrong!
Determining a religious belief is not science is not to say that the religious belief is not valid; just that it is not science.