[Mr. Lucky]

The Missouri Synod of the Lutheran Church tends to use the term "heretic" only in reference to member of the ELCA.

[annalex]

Good to know. Same principle: in order to be a heretic you have to hold a belief that is overall compatible. I would not call a Muslim heretic -- our beliefs have too little in common. Obviously the Lutheran confessions are not trying to insult one another, they are just being technical.

Heresy, according to the Oxford English Dictionary, is a "theological or religious opinion or doctrine maintained in opposition, or held to be contrary, to the Roman Catholic or Orthodox doctrine of the Christian Church, or, by extension, to that of any church, creed, or religious system, considered as orthodox. By extension, heresy is an opinion or doctrine in philosophy, politics, science, art, etc., at variance with those generally accepted as authoritative."

[...]

the term "heresy" has no purely objective meaning: the category exists only from the point of view of speakers within a group that has previously agreed about what counts as "orthodox". Any nonconformist view within any field may be perceived as "heretical" by others within that field who are convinced that their view is "orthodox";

Wiki

[Fischer1483]

Quote: "The Missouri Synod of the Lutheran Church tends to use the term 'heretic' only in reference to member of the ELCA."

And, is there a problem with that? :-)