Heresy comes from the Greek word for "choose" and it always means to pick-and-choose what to believe, against reason.
There are two faults of faith: doubt, or rejecting belief when there's a good reason for it; and superstition, or having faith when there's no good reason for it. (Similarly, the two faults of hope are despair and presumption.)
Heresy means picking one of those sides of faith. Superstitions are heresies because there are no good reasons to believe in things like anti-vax, horoscopes, tarot cards, knocking on wood, and anti-aging-cream.
Doubts are heresies because there are good and established reasons to believe in things like the moon landing, the Big Bang theory, and evolution.
There are two faults of faith: doubt, or rejecting belief when there's a good reason for it; and superstition, or having faith when there's no good reason for it. (Similarly, the two faults of hope are despair and presumption.)
Heresy means picking one of those sides of faith. Superstitions are heresies because there are no good reasons to believe in things like anti-vax, horoscopes, tarot cards, knocking on wood, and anti-aging-cream.
Doubts are heresies because there are good and established reasons to believe in things like the moon landing, the Big Bang theory, and evolution.