Romans 8:12-14 meaning

Paul calls the Roman Christians who received this letter brethren, again reminding us that these are believers whose faith is spoken of throughout the world; believers with whom Paul wants to make common cause (Romans 1:8). But that is threatened by the competing Jewish "authorities" seeking to displace the authority of Paul. This letter to the Roman believers will also help Paul's ministry partners Aquila and Priscilla, who host a church in their house in Rome, to counter the arguments of the competing Jewish "authorities" (Romans 16:3; Acts 18:2, 18, 26).

Paul makes a conclusion here, based on his reasoning in verses 1-11: So then, brethren, we are under obligation, not to the flesh, to live according to the flesh (v 12). 

He is telling the Roman Christians, once again, that they are freed from the flesh, and are now obligated to God. They have given themselves to Him. The flesh has no claim over them, and they are no longer condemned (v 1).

For if you are living according to the flesh, you must die (v 13). The wages/consequences/results/payment of sin is still death; nothing has changed in that regard. In this letter Paul is responding to the slanderers' assertion that Paul teaches that Jesus's blood covers every sin, no matter what, that if you could sin and get away with it, then of course you would, therefore Paul teaches we ought to sin (6:1). 

Paul answers this slander with the question, "Why would you? Sin is death. You don't understand what's going on, you have a faulty perspective if you say that." Paul will not let his readers forget that if you are living according to the flesh, you must experience death, death from which you have been delivered; the flesh will always kill, it will disconnect you from living the life God intended, but you don't have to live that way anymore. 

The alternative is life. Through the freedom Jesus gives us, and through the resurrection power He gives us, we can now choose life, so why would we choose death instead? The key is to adopt a true perspective, through the eyes of faith, that sees things as they actually are—to see life as life and death as death. 

How do you experience daily this newness of life? If by the Spirit you are putting to death the deeds of the body, you will live (v 13). Stop listening to your flesh, stop following it. It only ends in death. Follow the Spirit, by faith in the grace and strength of God, turn your eyes to Him, and you will live. Why would we do that? Because if we adopt the true perspective Paul offers us—of who we are and how we can gain maximum fulfillment—then this is just what makes sense to choose.

It is important to note that although Paul says we as believers are obligated to God, that does not mean we have no choice. God has given us the amazing ability to choose, even when we are indwelt with His Spirit. We are forever rescued from eternal condemnation, but we still experience negative consequences of sin if we walk in our fallen nature. Our obligation to God is our responsibility to use the superpower gift He has given us (the Holy Spirit) rather than wasting it.

In verse 14, Paul comments on the relationship that Christians have with God; For all who are being led by the Spirit of God, these are sons of God. There is a strong theme throughout the Bible of Christians being the adopted children of God. We were formerly apart from God, lost and living in our sin, and then Jesus Christ (through His death and resurrection) redeemed us, restoring our connection to God. 

As we will soon see, however, this seems to refer to the Roman practice of an adoption ceremony welcoming a son to manhood, and into the position of being an inheritor that manages the family. Paul has been emphatic that we cannot out-sin the grace of God. But in setting forth a true perspective of the amazing benefits of walking in the Spirit, Paul will show us there is much more in store for those who walk in the obedience of faith than just life and peace. There is the great reward of being restored to our original design to reign over the earth in harmony with God and others.