The word doctrine comes from a Latin word, doctrina, which means, “that which is taught.” and it refers to the Christian teachings on Scripture, God, man, Christ, salvation, church, and the end of all things. Simply put, doctrines are organized teachings by their subjects. The Doctrine of something is simply the organized explanation of what is taught about that something. When it comes to Jesus, who Jesus is and what he did, is simply the doctrine of Christ.
Illogical and Irrational
It is illogical, and irrational to say 'doctrine' does not matter or is not necessary or important. Simply asking "what is the bible?" and ANY sort of answer to this question is formulating or explaining some sort of personally held 'doctrine' of the bible. Answering the question "Who is Jesus?" is formulating or explaining a doctrine of Jesus. The illogical concept of 'doctrine does not matter' is a doctrine of why it does not matter and is contradictory from its premise.
God and The First Organized Doctrines
God himself first organized and formulated the very basic teachings that relate to mans relationship with God and man's relationship with man in the 10 Commandments (Ex. 24:12). That which is taught was meant to show man how they are fallen and sinful. A standard of only 10 basic commands that they could not even keep perfectly; but something to strive toward imperfectly, and have faith in God, that he will have mercy on them and redeem them from their short comings revealed through the 10 Commandments. Paul explains this in Romans 3.
The Pharisees
The Pharisees and other Jewish religious groups failed to understand this. They created over 600 man-made additional laws in an attempt to justify themselves as able to keep the 10 Commandments. Their invented doctrines was an attempt to side step the fact the 10 Commandments exposed them as sinners and reveal their need for mercy and a savior. They failed to see and understand true doctrine.
Since ALL people can not escape doctrine and believing in some sort of teaching (even if it is a teaching that states doctrine does not matter) we see that there are different kinds of doctrine. The Pharisees show us there is bad doctrine and Jesus shows us there is true doctrine.
Attempts to avoid and or side step knowing true doctrine ultimately is an attempt to justify one owns feelings and desires. Where bad doctrine naturally leads to false doctrine. This comes from the natural desire for self-righteousness.
Jesus and The Fulfillment of Doctrine
Jesus taught on the doctrine of God (John 4:24), the doctrine of humanity (Mark 10:6), the doctrine of sin (Matthew 15:18-19; John 8:34), the doctrine of redemption (John 3), the doctrine of the sovereignty of God (John 6), the doctrine of the church (Matt 16), the doctrine of things to come (Matt 24), and there are hundreds of verses that Jesus spoke that can all be organized by subject. Thus to believe that doctrine does not matter is a belief that Jesus himself opposed.
How do you know WHAT to believe?
The Apostles themselves made it explicitly clear the importance of true or 'sound' doctrine. When Paul (under the direct influence of the Holy Spirit) wrote to Timothy, he states: "...constantly nourished on the words of the faith and of the sound doctrine which you have been following" (1 Tim 4:6). In his next letter to Timothy (under the influence of the Holy Spirit) Paul gives a explicit warning: "...For the time will come when they will not endure sound doctrine; but wanting to have their ears tickled, they will accumulate for themselves teachers..." (2 Tim 4:3). In his letter to Titus he also very clearly states: "holding fast the faithful word which is in accordance with the teaching, so that he will be able both to exhort in sound doctrine and to refute those who contradict." (Titus 1:9). Lastly, in his first letter to Timothy, Paul states this: "If anyone advocates a different doctrine and does not agree with sound words, those of our Lord Jesus Christ, and with the doctrine conforming to godliness, 4 he is conceited and understands nothing;"
Therefore; when considering the absolute existence of bad and true doctrine; anyone that states doctrine does not matter, does not fully understand 'that which is taught' from God and his Apostles.
What is Sound Doctrine?
"Sound Doctrine" is simply anything non-contradictory that agrees with what is taught in scripture. Bad doctrine is recorded in scripture as well. That which was taught by Satan to deceived Eve. That which is taught by The Pharisees and many other instances in scripture where people are recorded as teaching something that is not of God. This gives us a prime contrast and helps us discern true doctrine as well.
How do we know that which is Sound Doctrine?
Any teaching from scripture that magnifies faith in the person, teachings, and works of Jesus Christ and of which solely gives all praise and glory to God. God's recorded redemptive history, from the Old Testament all the way to the close of scripture, is for God's Glory and to reveal The Christ for all the world to see and know!
True Doctrine
Those who have placed their faith in The Gospel message (life, death, and resurrection of Jesus) have already accepted the Doctrine of Christ and the Doctrine of the Resurrection. From there, because they have been granted repentance, born again, baptized by the Holy Spirit, and adopted by God through the work of Jesus Christ; are entrusted to continue in Sound Doctrine and grow in knowledge of God.
Genuine Faith compels us to desire to know God more and more. We know God more and more by learning and believing the truths he has revealed about himself in scripture and applying our faith and trust in Him in our daily lives.
NO one is saved by how much doctrine they know. Knowing vast amounts of bible verses and having the ability to articulate complicated eternal truths does NOT make anyone righteous or justified before God. The reverse is also true. No one is saved by how little importance they place on knowing The Bible either. Trusting in your feelings and emotions over divinely revealed truths written in scripture does not escape anyone from the natural attempt to justify themselves. No one is justified before God by avoiding 'doctrine'. The Pharisees avoided (were blind to) the true doctrine of Jesus Christ and invented their own 'tests' of faith to justify themselves; much like emotionalistic christians today.
How do you know what a FALSE Doctrine is?
This is a problem for those who avoid learning true doctrine. At some point, even they have to admit a certain teaching is false because they even have to compared it to a true doctrine. To know what is false, you first have to know what is true. If those who belittle doctrine are confronted with the statement: "Jesus is not the way, not the truth, and not the life, everyone man may come to God and go around me" they are forced to either say this statement may be true, or they are forced to compare it to John 14:6 and unwillingly validate true doctrine and determine that statement to be false (or bad doctrine). Also, this doctrine and the Gospel Message are so critical, that it impacts the eternity of someone's soul! Thus, proving the absolute importance of knowing sound doctrine.
Doctrine IS the CONTENT of Faith
What do people have faith in? If anyone claims to have faith IN Jesus, then they must believe a doctrine about Jesus. Jesus was born by a virgin, lived a sinless life, was crucified, died and rose from the dead three days later; Jesus is Lord God and Savior. THAT is a doctrine that Christians must have faith in, in order to be saved (1 Cor 15)!
The question all humanity must ask themselves is; WHAT is their faith in? The "what" is Doctrine. But the "what" can either be false and bad or true when it comes to eternal redemption and salvation.
Relationship With God
The more we get to know someone the closer we are with them. The more we get to know God, the closer we are to him. He teaches us His eternal truths about himself and we grow to trust, obey, and have faith in Him more and more. He empowers us to not just be hearers of his truths but be doers (James 1:22). As we live out our trust and faith in his revealed truths, he grows us, matures us, and makes us more wise in discerning his will and truths (Ps 51:6). This relationship is founded on and is directly connected to studying, knowing, and trusting his word (Ps 119). Because it is The Holy Spirit through scripture that grows us closer to him (Col 1:9; 2 Tim 3:16).
The relationship is not a one way street based on your feelings and emotions any given day. His word is true and his will is unchanging; that is why we can absolutely trust in him and depend on him in our daily lives.
The desire to know God's word and learn more and more about who he is, what he is done, and what he has promised is far from 'legalism'. Ironically those who confuse knowing scripture with legalism tend to be antinomialist. Which is just as spiritually harmful as legalism but at the other end of the spectrum. Antinomialist only think they have a relationship with God, when in fact their lives are lived in a self-righteous lawless state; where their feelings, desires, and emotions knowingly or unknowingly invent their own version of God and invent their own standards of what pleases their version of god. Twisting and misunderstanding God's word while incorporating feelings and emotions as truth is often used to justify this state of mind and belief.
True Doctrine is Freedom
Jesus promised us freedom in him! Freedom from the slavery of sin and freedom to have the ability to trust, obey, and have faith in who He is and what he has declared in scripture. Though we are not perfected yet, we are no longer slaves to sin and the penalty of it. We are restored, can know him, and long for the day He brings us home to him. Trusting and beveling in his true doctrines he has declared frees us to follow him and glorify him.
Summery:
Doctrine is 'that which is taught' or the content of a teaching and faith
"Doctrine does not matter" is a doctrine
"Doctrine is not important" is a doctrine
There is false and bad doctrines and true doctrine
True Doctrine must first be accepted in order to have saving faith (The Gospel message).
God empowers those whom are saved to understand true doctrine.
Knowing true doctrine protects against believing in false or bad doctrine.
Jesus taught doctrines of God
The Apostles (via The Holy Spirit) instructed believers to hold to Sound (true) Doctrine.
True Doctrine is supremely important and ultimately matters.