Heresy is when someone believes wrong things about God or the Bible. People who teach heresies are called false teachers. Heresies are dangerous to God’s people (see: 2 Peter 2:1-3). They cause people to do things that do not honor God.
Heresies also cause people to disagree and to argue. Paul said that divisions among God’s people are caused by people’s sinful nature (see: Galatians 5:19-20). Paul told Christians to remove a person who causes division if that person keeps on doing and believing wrong things and does not turn back to the right way (see: Titus 3:10-11).
The writers of the New Testament often warned about false teachers. The writers of the New Testament also taught what was true about God after heresies had caused Christians to not understand the right things about God (see: 2 Corinthians 11:1-15; Galatians 1:6-9; Colossians 2:8, 16-23; 2 Thessalonians 2:1-4; 1 Timothy 1:3-7; 1 John 2:18-19; 4:1).