He espoused doctrines that mainstream Christians denounce as heretical. Several enemies testified that Cranmer had encouraged heresy and had written heretical works. A few crusades were waged within Christendom against groups that were considered heretical and schismatic. He was wary of Gravesend's open acceptance of "heretical" sects. Iconoclasm was later definitively classed as heretical. He was later anathematised and some of his writings condemned as heretical. Gnosticism became the first group to be declared heretical. The Definition implicitly addressed a number of popular heretical beliefs. Yet after the danger of spreading heretical writings passes, the Bible ought to be translated. Some Christians later burned libraries, and especially heretical or non-canonical Christian texts. By 1215, the Waldensians were declared heretical and subject to persecution. Considering these heretical, he reviled them with curses. Teitelbaum was a fierce opponent of Zionism, which he decried as inherently heretical. Elizabeth and her advisers perceived the threat of a Catholic crusade against heretical England. The Church used it as a term of offence against a group they considered heretical.