Titus 1:10-11 (ESV)
For there are many who are insubordinate, empty talkers and deceivers, especially those of the circumcision party.  They must be silenced, since they are upsetting whole families by teaching for shameful gain what they ought not to teach.
Why must a pastor be able to rebuke those who teach false doctrine? The above verse answers the question. Some say doctrine divides. That is not true. Doctrine is what unites those in the church, much more so than it separates us from those who do not hold to what we teach. False Doctrine divides, it upsets and causes quarrels. It not only places salvation in jeopardy, which is bad enough, but it also upsets and causes problems in this earthly life. False doctrine manifests itself in despair, and other great shame and vice.