False teaching or false doctrine is countered several places in the New Testament. Here are a few: Colossians 3:17-19, 1 Timothy 1:18-20, and 1 John 4:1-3.
The doctrine that Paul is talking about in 1 Timothy 4:16 is saving teaching. How do we know? “You will save yourselves and your hearers.” What saves is the gospel.
Obviously, the secondary doctrines and practices that divide Christians cannot all be right. Some are not important. Read Romans 14 several times. It is the primary doctrine, the gospel, that saves and sanctifies. “For the kingdom of God is not a matter of eating and drinking, but of righteousness, peace, and joy in the Holy Spirit, because anyone who serves Christ in this way is pleasing to God and approved by men” (Rom. 14:17-18).
Christians have used the word “doctrine” and the content of secondary teachings to divide saved people. To my knowledge, the Bible does not use the word “doctrine” that way. When Paul stood up to Peter in Galatians 2:14, the issue was saving truth. It was the same in Acts 11 and 15.
“As I began to speak, the Holy Spirit came on them as he had come on us at the beginning. Then I remembered what the Lord had said: ‘John baptized with water, but you will be baptized with the Holy Spirit.’ So if God gave them the same gift as he gave us, who believed in the Lord Jesus Christ, who was I to think that I could oppose God?” When they heard this, they had no further objections and praised God saying, “So then, God has granted even the Gentiles repentance unto life.” (Acts 11:15-18)The early creeds were designed to refute heretical teaching that did not save. The later confessions divided saved people from each other. Yet we call these confessions sound doctrine.
No! We believe it is through the grace of our Lord Jesus that we are saved, just as they are. (Acts 15:11)