Heresy is the persistent denial of the infallible teaching of the Catholic Church. A baptized Christian who teaches what is contrary to the indispensable teaching of the Catholic Church is called a heretic.

False teaching about the essentials of Christianity is a harmful and divisive sin that leads away from the truth. While challenges and disagreements about less serious matters may occur in the Church, heretical beliefs may lead to excommunication.

Catholics who fail to live up to the Church’s discipline and moral teaching can be forgiven but individuals who reject the Church’s teaching as revealed by God in Sacred Scripture and Tradition are no longer considered Christian.

Throughout its history, the Church has responded to false teachings of heresy with profound study that led to the formulation of creeds and other dogmatic statements.

Understanding what makes the errors of heresy untrue leads to a deeper understanding of the fullness of the truth taught by the Catholic Church.

The Church helps Catholics avoid error by including an Imprimatur and Nihil Obstat in books that do not contradict Catholic teaching.

Persistent denial of dogma:

Heresy is divisive:

There were also false prophets among the people, just as there will be false teachers among you, who will introduce destructive heresies and even deny the Master who ransomed them, bringing swift destruction on themselves. Many will follow their licentious ways, and because of them the way of truth will be reviled. In their greed they will exploit you with fabrications, but from of old their condemnation has not been idle and their destruction does not sleep.

2 Peter 2: 1-3

Heresy is a serious matter:

The practice of the Church has always been the same, as is shown by the unanimous teaching of the Fathers, who were wont to hold as outside Catholic communion, and alien to the Church, whoever would recede in the least degree from any point of doctrine proposed by her authoritative Magisterium. Epiphanius, Augustine, Theodoret, drew up a long list of the heresies of their times. St. Augustine notes that other heresies may spring up, to a single one of which, should any one give his assent, he is by the very fact cut off from Catholic unity. “No one who merely disbelieves in all (these heresies) can for that reason regard himself as a Catholic or call himself one. For there may be or may arise some other heresies, which are not set out in this work of ours, and, if any one holds to one single one of these he is not a Catholic”.

Pope Leo XIII, Satis Cognitum, 29 June 1896

Errors about the faith:

Combatting misunderstandings about God:

Correcting heresy with a creed:

Incredulity is the neglect of revealed truth or the willful refusal to assent to it. “Heresy is the obstinate post-baptismal denial of some truth which must be believed with divine and Catholic faith, or it is likewise an obstinate doubt concerning the same; apostasy is the total repudiation of the Christian faith; schism is the refusal of submission to the Roman Pontiff or of communion with the members of the Church subject to him.”

Catechism of the Catholic Church 2089

Tools in the struggle against error:

The Truth, Goodness, and Beauty of the Catholic Church

The Christianity of history:

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