What does the Bible say about teaching different doctrine?

In 1 Timothy 6:3-5, the Apostle Paul emphasizes that anyone who teaches a doctrine contrary to the sound words of Jesus is puffed up and lacks understanding. He exhorts Timothy to guard against such teachings and states that this different doctrine often leads to disputes, envy, and strife among believers. The church is warned about the dangers of false teachings which can arise even from within its ranks, highlighting the importance of sound doctrine that aligns with the gospel's core message.