Heresy is a doctrinal view that deviates from the truth, a false teaching. We are warned against it in Acts 20:29-32 and Phil. 3:2. Heresies include teachings that Jesus is not God, the Holy Spirit is not a person (i.e., Jehovah's Witnesses, Christadelphians, The Way International), men may become gods (Mormonism), there is more than one God (Mormonism), Jesus lost His divinity in Hell and finished the atonement there and that good works are necessary for salvation (all cults say this), to name a few.