Heresy is understood today to mean the denial of revealed truth as taught by the Church. ... Formal heresy is "the wilful and persistent adherence to an error in matters of faith" on the part of a baptised member of the Catholic Church. As such it is a grave sin and involves ipso facto excommunication.

What is heresy according to the Bible?

Heresy in Christianity denotes the formal denial or doubt of a core doctrine of the Christian faith as defined by one or more of the Christian churches. ... In the East, the term "heresy" is eclectic and can refer to anything at variance with Church tradition.

Is heresy a crime?

Starting in medieval times, Muslims began to refer to heretics and those who antagonized Islam as zindiqs, the charge being punishable by death. ... In some modern day nations and regions, heresy remains an offense punishable by death.