“Watch your life and doctrine closely. Persevere in them, because if you do, you will save both yourself and your hearers.” (1 Tim 4:16NIV)
A ‘doctrine’ is what the whole Bible teaches about a particular topic, such as about God, Jesus, sin, Salvation, condemnation, etc.
A person is guided by his ‘doctrine’ and makes him what he is. Your living style depends on what teaching (doctrine) you have. Ass such, one must have a sound doctrine to live a godly life.
One much have a sound doctrine and follow this sound doctrine. Failing which, you may life an ungodly life and go to condemnation.
Those who teach must teach sound doctrine, totally base on the whole Bible and follow the sound doctrine of the Bible. This way, those who teach will save both his life and those who follow his teaching.
Whereas, those who teach and follow bad or false doctrine will be what our Lord Jesus Christ says,
“Woe to you, teachers of the law and Pharisees, you hypocrites! You travel over land and sea to win a single convert, and when he becomes one, you make him twice as much a son of hell as you are.” (Matthew 23:15)
To have and follow a sound doctrine, study the Bible daily and always pray.
God bless you.