The carnal mind can not perceive the Spiritual things of God and this is how Satan can enter the mind and will twist the word of God as Satan is the Father of lies.
1John 2:21 I have not written unto you because ye know not the truth, but because ye know it, and that no lie is of the truth.
1John 2:22 Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son.
1John 2:23 Whosoever denieth the Son, the same hath not the Father: (but) he that acknowledgeth the Son hath the Father also.
1John 2:24 Let that therefore abide in you, which ye have heard from the beginning. If that which ye have heard from the beginning shall remain in you, ye also shall continue in the Son, and in the Father.
1John 2:25 And this is the promise that he hath promised us, even eternal life.
1John 2:26 These things have I written unto you concerning them that seduce you.
1John 2:27 But the anointing which ye have received of him abideth in you, and ye need not that any man teach you: but as the same anointing teacheth you of all things, and is truth, and is no lie, and even as it hath taught you, ye shall abide in him.
Vs. 27 is that anointing of the Holy Spirit that opens our Spiritual eyes and ears to understand that which has already been spoken by Jesus as the Apostles bear witness in their writings of what Jesus taught. If we are only leaning on what man teaches, especially in the hand me down traditional teachings that do not line up with the full context of scripture, then we can lose sight of that which Jesus already taught. That is why there are so many different teachings as many rely on man's theologies and doctrines to teach them, but do not study the scriptures for themselves for what has already been written as they do not Spiritually discern what they are being taught, 1 John 4:1-6.