Fr. Seraphim to a Protestant inquirer:

The word "heretic" . . . is indeed used too frequently nowadays. It has a definite meaning and function, to distinguish new teachings from the Orthodox teaching; but few of the non-Orthodox Christians today are consciously "heretics," and it really does no good to call them that. . . .A harsh, polemical attitude is called for only when the non-Orthodox are trying to take away our flocks or change our teachings. (Monk Damascene Christensen, Not of This World: The Life and Teachings of Fr. Seraphim Rose [Fr. Seraphim Rose Foundation, 1993], pp. 757-58.)