In the biblical sense Doctrine is simply defined as “that which is taught.”
Isaiah 28:9 says, “Whom shall he teach knowledge? and whom shall he make to understand doctrine? them that are weaned from the milk, and drawn from the breasts.”
It’s much easier to understand doctrine when you are weaned from the milk. All it means is it’s your own perception that matters, i.e., to be able to hear, see, think and understand for yourself than relying on the opinions of others.
Doctrine may not be good for everyone, it’s not meant for infants. “For everyone who partakes only of milk is not accustomed to the word of righteousness, for he is an infant. But solid food is for the mature, who because of practice have their senses trained to discern good and evil.” Hebrews 5:13-14
You got to have all your senses trained to discern good and evil. You’ve a problem if all you know about God is only your church doctrine. You got also to be weaned; to be detached or drawn even from the breasts of your leaders and look clearly for yourself into the perfect law of liberty.
Ezekiel 3:1-3 says, “Then He said to me, “Son of man, eat what you find; eat this scroll, and go, speak to the house of Israel.” So I opened my mouth, and He fed me this scroll. He said to me, “Son of man, feed your stomach and fill your body with this scroll which I am giving you ” Then I ate it, and it was sweet as honey in my mouth.“
Doctrine is not man-made, it is all about the scroll; fill your whole body with what you find in it. “The law of the LORD is perfect, restoring the soul; The testimony of the LORD is sure, making wise the simple. The precepts of the LORD are right, rejoicing the heart; The commandment of the LORD is pure, enlightening the eyes.” Psalm 19:7-8
“Jesus answered them, and said, My doctrine is not mine, but his that sent me. If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself. He that speaketh of himself seeketh his own glory: but he that seeketh his glory that sent him, the same is true, and no unrighteousness is in him.” John 7:16-18
Deuteronomy 32:1-6 says,
 Give ear, O ye heavens, and I will speak; and hear, O earth, the words of my mouth.  My doctrine shall drop as the rain, my speech shall distil as the dew, as the small rain upon the tender herb, and as the showers upon the grass:  Because I will publish the name of the Lord : ascribe ye greatness unto our God.  He is the Rock, his work is perfect: for all his ways are judgment: a God of truth and without iniquity, just and right is he.  They have corrupted themselves, their spot is not the spot of his children: they are a perverse and crooked generation.  Do ye thus requite the Lord , O foolish people and unwise? is not he thy father that hath bought thee? hath he not made thee, and established thee?
Please note, if the doctrine you hold of him is corrupted; you also are no longer his. Verse 5 said “They have corrupted themselves, their spot is not the spot of his children: they are a perverse and crooked generation.”
The Bible warns us to be careful about what doctrines we believe and teach. The New Testament repeatedly emphasises the value and importance of sound doctrine, it’s got to be sound, really sound instruction ( 1 Tim 6:3 ), and a pattern of sound teaching ( 2 Tim 1:13-14 ). If the apostles were able to defend the faithful proclamation of the gospel we also should strive for the same mastery ( Gal 1:8 )
The apostle John said believers should develop for themselves three tests for discerning authentic spirituality:
- believe right doctrine ( 1 Jo 2:18-27 ),
- obey right doctrine (2:28-3:10), and
- give expression to right doctrine with love (2:7-11).
What does it mean, and is it important for us today? “Much in every way: chiefly, because that unto them [us] were committed the oracles of God.” Romans 3:2