In traditional Catholic theology, the term material heresy refers to an opinion that is objectively contradictory to the teachings of the Church, and as such heretical, but which is uttered by a person without the subjective knowledge of its being so. A person who holds a material heresy may therefore not be a "heretic" in the strict sense. Material heresy is distinguished from "formal heresy", i.e. a heretic opinion proposed deliberately by a person who is aware of its being against the doctrine of the Church.
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Material heresy Wikipedia(Text) CC BY-SA