Perhaps I painted the concept of heretic too broadly as you indicate. My main point, though, is that the term “heretic” is a measurement of sorts or a comparison with some standard, and the issue is who or what sets up the standard on which the measurement is made? I assume every faith has its own measuring stick and who is or who is not a heretic (or an infidel) depends on which measuring stick is applied.
Yeah. So how indeed and with what standard can we judge? I suppose those who believe in a personal God will ask Him for guidance.