For the same reason we don't eat just potato chips the believer needs to eat a better stronger diet than just a few verse...but they also need the power of the Spirit inside them shaping them with that Word.
So roll up your sleeves, put your mind in gear, be totally ready to receive the gift that’s coming when Jesus arrives. Don’t lazily slip back into those old grooves of evil, doing just what you feel like doing. You didn’t know any better then; you do now. As obedient children, let yourselves be pulled into a way of life shaped by God’s life, a life energetic and blazing with holiness. God said, “I am holy; you be holy. [1 Peter 1:13-16]