EPPH - Every Painter Paints Himself

Ever since I became aware that masterpieces of Western art tend to make more sense viewed through the ideas of esoteric Christianity than through the Secular Church’s religious dogma, I have been curious why art historians write as though there was only one Church in the Middle Ages and Renaissance when – even before the Reformation – that one Church was really two. There may have been one Church dogma but there were plenty of other beliefs, some completely at variance with general understanding of Christianity. The latter would appeal to creative minds in any age even if the papacy then had not been totally discredited by corruption, simony and moral degradation.