Question from Jeremy:
Will you please explain to me the difference between an atheist and a heretic?

Answer by SmartLX:
Atheists don’t believe in a god. Heretics commit heresy – they say and/or do things which contradict religious dogma.

Heresy is different from blasphemy, which is specifically a show of irreverence toward religion. It’s possible to be heretical without being blasphemous (for example by praising the actions of a church while debunking its beliefs) or to be blasphemous without being heretical (for example by insulting a god without questioning its existence) but it’s usually easier to be both at once.

All outspoken atheists and agnostics are also heretics in the eyes of the religious, because openly questioning the existence of an established god is a basic form of heresy. Silent or closeted atheists (the kind churches prefer) may not be heretics, especially if they pretend to worship out of some social obligation.

Not all heretics are atheists; in fact, the word is now most often used to describe those with religious beliefs that differ from the speaker’s to a relatively small degree. To a Catholic, a Muslim is a heretic, but Muslim beliefs are so far removed that the words “pagan” or “heathen” might seem more appropriate. A Catholic is more likely to use “heretic” to describe a Protestant, or a Mormon. Atheists may again be called “heathens”, or else unique words like “unbelievers” or “godless”.

Generally speaking, the word “heretic” has been de-emphasised when heresy has ceased to be a criminal offence. There are still places where heresy can get you killed, legally or otherwise, and there the word is still in regular use. For the rest of us living in pluralistic societies, heresy is a somewhat antiquated concept.