Galatians 5v16: But I say, walk by the Spirit, and you will not gratify the desires of the flesh.
The more you focus on trying not to gratify (indulge, satisfy) a desire, the more difficult it is. As an innocent example: if you’re on a diet, trying to resist a piece of chocolate cake or something, then watching someone else eating it is not going to help you; constantly thinking “I must not eat that, I must not eat that” is not going to help you. You’d be better off focussing on something completely different to take your mind off it.
It’s the same with sinful desires. I don’t have the exact quote, but John Owen in The Mortification of Sin says something to the effect that, once you’ve confessed sin and asked God for forgiveness, it doesn’t help to keep dwelling on it. If your mind is set on “I must not commit this sin, I must not commit that sin”, then those sins are constantly on your mind, and the more your mind is focussed on your sin, the more you’ll be tempted to sin. We’re better off focussing our minds elsewhere.
Thomas Chalmers preached a sermon called The Expulsive Power of a New Affection. A new affection for Christ has the power to expel sinful desires from our hearts.
Paul is instructing the Galatians to avoid gratifying the desires of the flesh by focussing instead on walking by the Spirit. He doesn’t give them two instructions: walk by the Spirit and don’t gratify the desires of the flesh. It’s “walk by the Spirit and you will not gratify the desires of the flesh”. Do the first and the second will happen automatically. You can’t walk by the Spirit and gratify the desires of the flesh at the same time, so as long as you’re walking by the Spirit, by default you will not be gratifying the desires of the flesh.
Apparently the phrase “walk by the Spirit” implies both power and direction, which prompts two questions: which direction is the Spirit going in? and how do we get the Spirit to give us the power to walk that way?
For the direction, I think it will be helpful to look at John 16:13-14.
The Spirit will glorify Christ, and if we’re walking by the Spirit, our lives will be heading in the same direction: glorifying Christ. To “glorify” means to praise, or to describe or represent as admirable. If we’re walking by the Spirit, our lives will point to Christ and represent him as glorious.
Now you might be thinking “that’s really challenging; my life isn’t pointing to Christ as much as it should; I really need to work on that”, and there’s probably some truth in that, but we’ve only answered one of the questions. We’ve got the direction but not the power. The power to live our lives in a way that glorifies Christ doesn’t come from feeling ashamed of our past failures, it comes from the Spirit.
And how do we get the Spirit’s power? Let’s go back to Galatians 3:2-5.
We received the Spirit when we first believed the gospel by hearing with faith, and God still supplies (present tense) the Spirit to you by hearing with faith. So if you feel like you’re lacking the Spiritual power to walk in a way that glorifies Christ, go back to the gospel, and believe it. Believe that God has forgiven you. Jesus paid for all of your guilt on the cross. And that’s not conditional on you doing anything for him in return; he did it to show the riches of his glorious grace.