This is a purity argument, a theological argument, it has nothing to do with gathering voting numbers for Catholic voters, or Jews, or Protestants, or Muslims, or Mormons, etc.
The day the Vatican starts purging it’s rolls and offering a different set of numbers for how many Catholics are on the planet, then you can request pollsters to ask the Catholic voter if he is no longer Catholic, or has been told by the Vatican that he has been removed from being counted as Catholic, then the pollster can not count him as Catholic.
Let me get this straight; you are conducting a conservative Christian purity test, but are objecting to a purity test within your purity test?