Over the years that I have been a Christian, I have encountered many individuals and churches who say, "Doctrine doesn't matter" or, "We don't need doctrine, we just believe the Bible." Sounds good, but the understanding of what the Bible means is so varied that, if we do not formulate a clear understanding of what we believe, we can become totally confused. The problem is, if we don't know what we believe, then we can't say what we don't believe.
Doctrine simply means teaching - what we believe and, by implication, what we do not believe. Knowing what we believe (and why we believe it) will protect us from the many false teachings promulgated by "wolves in sheep's clothing" who constantly prowl around the Body of Christ.
Take, for instance, the very simple and basic Statement of Faith of CFS:
1) The Holy Scriptures, in it's original form, is the inerrant Word of God.
If we do not believe that Scripture is the Word of God, we may be persuaded that other books - whether the "scriptures" of world religions or the writings of individuals - have equal value. We may even seek to subject the truth of the Word to teachings found elsewhere. And, if we believe that the Bible merely contains the Word of God, rather than is the Word of God, then we will be free to throw out any passages that we don't particularly like. At the same time, if we don't qualify that it is the original form of Scripture that is the inerrant Word of God, then we can begin to build doctrines on the faulty translations of man. (I once heard a man preach a full hour sermon on a word that doesn't even appear in the Greek!)
2) There is only one God who reveals Himself as Father, Son, and Holy Spirit.
If we do not hold to this doctrine, we can fall into the trap of believing that the gods worshipped by the world's religions are the same as the God of the Bible. How many times have you heard someone say something like, "Oh, it doesn't matter what you call God - it's still the same?" No, it is not the same. The God of the Bible is the One who manifested Himself in the Person of the Lord Jesus Christ. Any god of whom that cannot be said is not the same as the God of the Bible. Many Christians today are being lured into the worship of false gods, simply because they have never taken hold of this doctrine.
3) We are separated from God due to sin.
Failure to understand this simple truth (doctrine) leads people to believe that "we (all people) are all God's children" and that therefore everyone has access to God. Yet Jesus very clearly said that this is not true. (John 8:44) If we do not believe that we are separated from God by sin, then there is no motivation to get back to Him; if we do not believe that others are separated from Him, then there is no motivation to preach the Gospel.
4) God's Son, Jesus Christ, was born of the virgin Mary, died on the cross for our sins, and rose again on the third day.
If we are not fully convinced of these truths (doctrine) then we might be persuaded that Jesus was not fully God, or that He was not fully man, or that His death was just a tragic martyrdom that had no significance other than as an example to us, or that He didn't really die but only swooned, and that His resurrection was not a return to life, but just a return to consciousness. I have heard every one of these false doctrines taught - and every one of them undermines our salvation. Jesus had to be fully man, because only a man can take the place of man. Yet he had to be more than just a man, because one man, even if he were sinless, could only pay the price for one man - only the infinite God could pay the price for all mankind. His death was not a mistake or a tragedy, but the plan of God from the foundation of the world (Rev.13:8.) And His resurrection was the proof of His victory over death - without it, we could not be sure that our salvation had been won.
5) We can only be saved by repenting of sin, and accepting Jesus Christ as our Lord and Savior by faith as stated in John 3:16. (The faith mentioned here will produce actions) and
6)This salvation is provided by the grace of God. We cannot be saved through our own efforts, our works or by the intervention of man on our behalf.
Without these truths (doctrine) we may be convinced that we can save ourselves by our efforts, by obeying the Law, by building up enough good works to counter our bad or by some other expression of self-righteousness. On the other hand, if we don't believe that our faith will be expressed in actions, then we can fall for "cheap grace" and think that by saying a prayer we can secure our salvation, regardless of how we choose to live. Both legalism and libertarianism miss the point that God extends His grace to us freely in Jesus Christ, but accepting His grace for salvation means also accepting His grace to live as He requires.
Don't ever allow anyone to scare you away from doctrine. Doctrine is simply what we believe, and what we believe matters: it affects every aspect of how we live.