Galatians 1:7-8

7which is really not another [gospel]; but there are [obviously] some [people masquerading as teachers] who are disturbing and confusing you [with a misleading, counterfeit teaching] and want to distort the gospel of Christ [twisting it into something which it absolutely is not].

8But even if we, or an angel from heaven, should preach to you a gospel contrary to that which we [originally] preached to you, let him be condemned to destruction!