Here is what happens. We replace God, instead of loving God with all our heart, mind, soul and strength- we replace God and we become idolaters of the heart, and instead we worship and love our own selves. Since we now love ourselves with all our heart, soul, mind, and strength- we covet- we long for that which is forbidden. Out of that longing comes evil lusts and vile passions out of that comes inward uncleaness, and out of that comes the external act of sin in the members of our body- sexual immorality. Paul here is commanding that we kill, we put to death the members of our body. Now, listen, that is impossible to do just by keeping a set of regulations, why? Because in order to actually stop the indulgence of the flesh, in order to grow with a growth that is from God you have to not just deal with the outward members of the body- you have to go all the way down deep to the very cause of the problem. You have to solve the sin of being an idolater of the heart. You have to overcome the sin of self-love and self-worship and the only way to do that is through the transformative power of the gospel. The only way to do that is through the power of a relationship with Christ. By faith you identify with the transformative power of Christ, and you being to learn what it means to seek Christ with all your heart and delight your mind in Christ not on things of the earth. And then all the way deep down Christ changes you heart so that you actually love God with all your heart, and mind, and strength. You tear down the idols of your heart, you kill the all of the vile loves in your heart, and instead you grow in your love for Christ. And when you do that. When you, by the power of the gospel in your relationship with Christ are transformed from the inside all the way deep down in the love of your heart, guess what happens? It works its way all the way back up the chain.