Like most modern words, “Heresy” is used both vaguely and diversely. It is used vaguely because the modern mind is as averse to precision in ideas as it is enamored of precision in measurement. It is used diversely because, according to the man who uses it, it may represent any one of fifty things.
He has Christian heresies in mind, as in his 1936 book, The Great Heresies (p. 7). Cavalier Books. Kindle Edition.
Blithe Spirit 