There are two types of excommunication:
- automatic excommunication, which occurs as a result of the individual knowingly choosing a particular act, and which does not require any subsequent judgment by the temporal authority of the Church.
- excommunication brought by the temporal authority of the Church, either by the Bishop of a diocese or by the Holy See, which is a particular judgment of a particular individual(s) and situation
Apostasy, heresy, and schism, under Canon Law, carry the penalty of automatic excommunication. However, heresy should not be defined so broadly that any minor dissent from any Church teaching would be called heresy.
An act of heresy with the penalty of excommunication would have to be formal heresy, that is, a knowing choice to reject definitive Church teaching; this would generally pertain to fundamental doctrines on faith or morals, or to any infallible or definitive teaching which is required belief.