Probably the most important member of our bodies is our mind. It is here that the battle is won or lost. All the expressions of the rest of the body begin in the mind. God has given us a new heart, and He writes His word on our hearts and on our minds. But He did not give us a new mind. We must take on the mind of Christ through consistent obedience. As we draw near to God and abide in Christ, the Lord will write His words on our mind. That is one of the provisions of the new covenant. You are deeper than your mind; otherwise Paul could not say, "Set your mind on things above." The mind is a member, a very important member. What we think about it is very important. If through lack of discipline we allow our minds to wander, soon the rest of our body will be wandering after it.
"I beseech you therefore, brethren, by the mercies of God, that you present your bodies a living sacrifice, holy, acceptable to God, which is your reasonable service. And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God" (Rom. 12:2). Notice that this is an active place before God. In faith, by the mercies and grace of God, we must do this. My whole mind must be renewed to think the way God thinks. The provision of the new covenant is that He will write His word upon our minds. If we are actively looking to God and listening to Him, we will recognize His word. In that word is the grace to obey. But if we disregard His word, we will not know the grace of God. We will find ourselves struggling, trying to do the will of God in our own strength--and we will fail.
In the area of desires, what we allow our minds to dwell on is very important. We are commanded to set our minds on things above. "Finally, brethren, whatever things are true, whatever things are noble, whatever things are just, whatever things are pure, whatever things are lovely, whatever things are of good report, if there is any virtue, and if there is anything praiseworthy--meditate on these things" (Phil. 4:8). If we meditate on things we should not, we will find our desires aroused in the wrong direction. We are placing ourselves in a position where we can be enticed by our undisciplined desires. Then when desire has conceived, it will give birth to sin. Sin breaks our fellowship with God, the love relationship grows cold, and the sin no longer seems to be so bad. Our vision dims, and the Word of God does not have the power it once used to have in our lives. At this point we are well on our way to spiritual death.
How did it all begin? It began by not walking in the Spirit and putting to death the deeds of the body by the power of an endless life. We thought it was a small thing to entertain thoughts that were not pure. We did not realize what the consequences would be. We thought that the lack of discipline of our thoughts was not serious. But it is the little foxes that spoil the vines. Do not be deceived, my beloved brethren.