No doctrine created by man can secure us. We can state our doctrines, we can minister them to many, but only God Himself can secure us. So many people have taken the words written down for us, the scriptures, and made them to mean what they want them to mean, thus deceiving themselves, going their own way, following after man and his teaching, not even realizing that they are deceived. But God has given the Holy Spirit to lead us into all truth, and any doctrine man has established misses the mark that God has set for us.
The mark God has set is Himself, and Jesus Christ came to bring us into the reality of that. Only as we walk in the Spirit can we know God. Only as we do His will can we know His doctrine. Doctrine is not what saves us. The Lord Himself saves us. Salvation is in Him. Life is in Him. If we look to other things and think that we are "all right" by keeping a set of rules or abiding in a certain doctrine man has set down, we are deceiving ourselves.
There is a thinking which ultimately orders our lives: law or grace. Grace does teach us to live soberly, righteously, godly in this present world (Titus 2:12). The law by the spirit of life in Christ Jesus has made us free from the law of sin and death (Romans 8:2). What we believe does influence our walk, and more than we realize. If we believe doctrine, our thinking and our walk will be governed by what we believe. But if we have a relationship with God, if we have the Spirit of God to lead us and guide us, He's not going to lead and guide us in doctrine; He's going to lead and guide us in life. Will we be controlled by our minds or by the Spirit of God? Man can know doctrine down to the letter, yet not know God. But knowing God and doing His will allows man to know the true doctrine. This is what Jesus told us: "If you do My will, you will know My doctrine [teaching]" (John 7:17).