Last week in the five verses of Romans 8:12–17 we covered a lot of good ground.
Paul builds upon what we studied previously: that there is no condemnation for those who are in Christ Jesus because God sent his only Son to condemn sin in the flesh in order that we might live empowered by the indwelling Spirit, setting our minds on the Spirit, thus gaining life and peace. Because Christ is in us, we belong to him, and even though our bodies are weakened and will someday die, because God raised Jesus from the grave, we trust that he will do the same for us. What follows is based upon these precious truths.
Paul follows this train of thought with our obligation to God to put to death—by the Spirit— the deeds of the body (Rom. 8:13). It may sound like legalism to say that we are obligated to do something, but this is not something we are doing to earn our salvation. And the ‘doing’ of this obligation is not in our own strength. Look at the ground Paul has already covered and at what he is saying. The obligation and the ability to live a holy life are preceded by the fact that we are already Christians.
Romans 8:13 is the verse upon which the 17th Century Puritan John Owen built his treatise, The Mortification of Sin. Owen’s main thesis was that:
The choicest believers,
who are assuredly freed from the condemning power of sin,
ought to make it their business all their days,
to mortify the indwelling power of sin.
Owen makes the point throughout his book that we must be killing sin, or it will be killing us. Sin takes no holidays from endeavoring to shipwreck our faith, separate us from God, and destroy the fellowship of the church. Owen saw clearly what we seem to grasp only when times are tough—that we are in a spiritual battle every minute of every day. But when times are good, we Spirit-empowered believers may forget that we must be making every effort to grow in holiness and put to death our indwelling sin.
Friends, this is sanctification and it is the necessary product of justification in the lives of believers. We have been saved from the penalty and the power of sin, but, until the day we enter glory, we still live in the presence of sin. But have no fear, because all who are led by the Spirit of God are sons of God (8:14). Paul makes it clear that we have not been rescued from our bondage to sin only to fall back into bondage to fear because we have received—been freely given—the Spirit of adoption as sons, by whom we cry, “Abba! Father!” (8:15).
We are God’s tenderly beloved children. We therefore need not fear that we ‘aren’t measuring up,’ or that we are ‘failing miserably’ when we do sin. Remember, there is no condemnation for us if we are in Christ! There’s the battle with sin, and that is hard. But God has given us everything we need to live godly lives and fight our indwelling sin. Hear what Peter has to say:
His divine power has granted to us all things that pertain to life and godliness, through the knowledge of him who called us to his own glory and excellence, by which he has granted to us his precious and very great promises, so that through them you may become partakers of the divine nature, having escaped from the corruption that is in the world because of sinful desire. For this very reason, make every effort to supplement your faith with virtue, and virtue with knowledge, and knowledge with self-control, and self-control with steadfastness, and steadfastness with godliness, and godliness with brotherly affection, and brotherly affection with love. For if these qualities are yours and are increasing, they keep you from being ineffective or unfruitful in the knowledge of our Lord Jesus Christ. For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins. Therefore, brothers, be all the more diligent to confirm your calling and election, for if you practice these qualities you will never fall. For in this way there will be richly provided for you an entrance into the eternal kingdom of our Lord and Savior Jesus Christ. — 2 Peter 1:3-11
God gives us everything we need to live and fight, so (for this reason), live and fight! Make every effort! Be all the more diligent! The Spirit of God dwells in us and leads us, informing and empowering our efforts, giving us life, making us God’s children and heirs (see how Peter went there too?), and will someday give resurrection life even to our mortal bodies just as he did to Jesus’s body when he raised him from the dead!
Speaking of our inheritance, we looked at what this means for those in Christ, and particularly in the context of the closing thought of verse 17: suffering with Christ.
True Christianity does not deny that there are very important promises for this life—promises that God will be with us in trouble, provide an inner peace in turmoil, minister comfort when we are distressed, and never leave us. But the basic idea is not that we shall escape trouble here, but be given grace to go through it. And the blessings of our inheritance are almost entirely reserved for us in heaven.
Sisters, life is hard, but God is good. God’s goodness doesn’t eliminate the genuine difficulties of living in a fallen world, but it invests them with greater meaning and fills us with hope as we eagerly anticipate our heavenly home.
Speaking of which, if we are heirs of God and co-heirs with Christ, what does that mean about the inheritance that awaits us in heaven? We know that we will have a heavenly home prepared for us (John 14:1–3); and a heavenly banquet (Matt. 22:1–14; 25:1–13; Luke 14:15–24; 15:11–32); we will reign with Christ (2 Tim. 2:12; Luke 19:11–27); and our likeness to Christ will be perfect and complete (1 John 3:1–2). But the greatest portion of our inheritance, by far, is God himself.
Whom have I in heaven but you?
And there is nothing on earth that I desire besides you.
My flesh and my heart may fail,
but God is the strength of my heart and my portion forever. — Psalm 73:25–26
In fact, returning to the presence of his Father is the aspect of our inheritance that Christ himself longed for above all others.
“Father, the hour has come; glorify your Son that the Son may glorify you, since you have given him authority over all flesh, to give eternal life to all whom you have given him. And this is eternal life, that they know you, the only true God, and Jesus Christ whom you have sent. I glorified you on earth, having accomplished the work that you gave me to do. And now, Father, glorify me in your own presence with the glory that I had with you before the world existed. — John 17:1–5
And so, there is suffering for the present, especially as we are Christians and the world therefore hates us as it hated our Lord. Because we are identified with our Savior, in union with him, we identify with him in his sufferings as well as in his glory (Rom. 6:3–4). Jesus himself warned us of the suffering we would endure, not that we would fear, but so that we wouldn’t be surprised, but instead would have peace. “In the world you will have tribulation. But take heart; I have overcome the world” (John 16:33).
This lesson only covered five verses, but it’s so hard to keep the summary brief. Still, I pray that digging into and wrestling with these precious truths of our faith is as encouraging to you as it is to me.
 John Owen, Overcoming Sin and Temptation, edited by Kelly M. Kapic and Justin Taylor (Wheaton, IL: Crossway, 2006), 47.
 James Montgomery Boice, Romans, Volume 2, The Reign of Grace, (Grand Rapids, MI: Baker Books, 1992), 846.