So here’s the real question. If (for the sake of the argument) the Catholic Church is NOT the True Church:
Which Protestant denomination is the True Church? Remember, the True Church is a physical church, not a spiritual fellowship of believers. James 5:14 pretty much says that the True Church is a real, physical church.
Why would God allow the Catholic Church to be in error for 1500 years before correcting it? In the OT, God only allowed the Jews to be in error for a hundred years or so before sending Babylon/Assyria/Persia/etc… to ruin them and show them the Truth of God. Why would God allow the Catholic Church to be in error for 10x that amount of time?