Romans 8:5 For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit set their minds on the things of the Spirit. 6 To set the mind on the flesh is death, but to set the mind on the Spirit is life and peace. 7 For the mind that is set on the flesh is hostile to God, for it does not submit to God's law; indeed, it cannot. 8 Those who are in the flesh cannot please God.
Note on “flesh”: Flesh refers to our sinful nature. Our physical body is contaminated with sin and causes each of us to think and act contrary to our Creator God, Jesus. Proverbs 14:12 sums this up, “There is a way that seems right to man, but its end is the way to death.”
Thinking apart from the Word of God is thinking according to the things of the flesh. This thinking leads to death, even though it seems right at the time. Proverbs 23:12 instructs us not to withhold discipline from a child even if it painful to the child at the time. Hebrew 12:5-11 instructs us that the Lord disciplines us in a painful manner out of love for us and so we will experience the peaceful fruit of righteousness and He uses parental discipline as an illustration. Sinful thinking would think we are being loving to a child to withhold discipline, but withholding discipline from a child who needs it does that child and all around him long-term harm. Thinking according to the flesh also yields the fruit of the flesh (see Galatians 5:19-21; Ephesians 4:31; Colossians 3:7-9 for a few listings of the fruit of the flesh).
We are, as believers, to set our mind on the things of the Spirit. The Holy Spirit reveals truth to us (1 Corinthians 2:12), teaches us the truth and reminds us later what He taught us (John 14:6), and guides us into all truth (John 16:13). Knowing the truth leads to life and freedom (John 8:32; John 17:3; Romans 8:6). The mind that is set on the things of the Spirit is life and peace. Knowing this, we should desire to learn the things of the Spirit and practice, by the power of the Holy Spirit, what we learn. One indicator in our life that reveals where our mind is set is life and peace. The mind set on the Spirit is life and peace. Another indicator in our life that shows where our mind is set is our attitude toward God. If our mind is set on the things of the flesh we are hostile to God. Hostile isn’t merely shaking our fist at God and shouting hateful things to Him. Hostility is ignoring Him, making fun of Him, avoiding Him, not wanting to read what He has to say, doing what He says not to do and not doing what He says to do.
Is your mind set on the flesh or the Spirit? Determine the answer by the applying the indicators to your life. Is your life characterized by life and peace? Is your attitude hostile toward God? A “yes” answer to the first question and a “no” answer to the second indicate your mind is set on the Spirit. A “no” answer to the first question and a “yes” answer to the second indicate your mind is set on the things of the flesh. If your mind is set on the Spirit, don’t change the setting. If your mind is set on the flesh then you need to change the setting. You change the setting by repenting of your sin and believing the gospel if you are currently an unbeliever (Mark 1:15; 1 Corinthians 15:3-4; Romans 10:9) and then doing what a believer is to do as given in the next sentences. If you are a believer, you repent of your sin and begin to learn and practice the truth by faith in the Son of God. You need to take time to systematically read the Word of God asking the Spirit to teach you and move you to practice what you learn. Begin by reading Genesis, chapters one through eleven, and then begin reading Matthew and continue through the New Testament until you finish the book of Revelation.