Heresy is a belief contrary to established religious doctrine. The word comes from the Greek hairesis, meaning a choosing. It is the choice of a false doctrine. It is a deviation from orthodoxy. It is a rejection of the truth. It is a division. It is a scandal. It is a danger. It is a sin. It is serious. It is condemned. It is disciplined. It is corrected. It is refuted. It is anathema. It is heresy.

Heresy has a long history. Arius taught that Christ was a created being. The church condemned him at Nicaea. Nestorius taught that Christ had two persons. The church condemned him at Ephesus. Eutyches taught that Christ had one nature. The church condemned him at Chalcedon. Pelagius taught that humans could save themselves without grace. Augustine refuted him. Luther and Calvin were accused of heresy. They accused Rome of heresy. The Inquisition was established to suppress heresy. The Index of Forbidden Books was created to censor heresy. Heresy has divided the church. Heresy has caused wars. Heresy has killed people. Heresy is serious.

Major heresies in Christianity

• Arianism: Christ is a created being.
• Nestorianism: Christ has two persons.
• Monophysitism: Christ has one nature.
• Pelagianism: humans can save themselves.
• Gnosticism: salvation through secret knowledge.
• Donatism: the sacraments depend on the priest's purity.
• Iconoclasm: the destruction of icons.

Heresy is not always obvious. It is often subtle. It often contains truth. It often begins with a question. It often begins with a sincere seeker. It often ends in division. It often ends in error. It often ends in harm. The church must guard against heresy. It must teach the truth. It must define the truth. It must defend the truth. It must correct error. It must restore the erring. It must do so with love. It must do so with humility. It must do so with prayer. Heresy is the enemy. Truth is the weapon. Love is the motive. Orthodoxy is the goal. Heresy is the danger. Be on guard. Be faithful. Be true. Be orthodox. Be in Christ. Be in the truth. Be in the church. Be in the word. Be in the faith. Be in love. Be in heresy? No. Be in Christ.