What is the flesh? I've been thinking about this for a while and seeing it in operation in myself in greater degrees. Is the flesh just that part of us that does bad things? Below are my thoughts on the topic.
The flesh is that part of us that is committed ultimately to self and therefore to managing our lives apart from God. The thing that makes this definition, in my opinion, more helpful than the whole "the flesh is the part of you that does bad things" idea is that it more accurately encompasses the various ways our flesh works itself out in real life.
To see what I mean, take a look at the parable of the prodigal son in Luke 15. Jesus is actually illustrating this point. If we listen carefully and consider the audience of this parable, we can almost see that this parable is not quite as much about the "prodigal" son as it is about the one we usually forget: the elder son. The younger son, the prodigal who takes his inheritance from his father and runs off to live his own way easily fits our definition above: the son did not want his father -he wanted his own independent life, padded and provided for by his father's finances.
But look at the elder brother. Rather than running off like a foolish young man, living riotously and extravagently, the elder brother always does what the father asks. He even says so to the father, and the father does not dispute it. But consider the elder brother's reaction to the graciousness of the father to the younger brother when he returns. He is indignant. He rebukes his father, as if to say, "What are you doing? I always do what you want -these things are rightfully mine! Who are you to give them up to him to welcome him back, old man!?" In his bitterness, the elder brother refuses to join the feast set out for the prodigal son.
Can you see that the elder brother operates out of the same basic heart-attitude that the younger brother did? He doesn't want his father. He wants to manage his life apart from a relationship with his father. He wants his father's things, not his father. The only difference between the two young men is their approach.
The younger brother takes the classic "bad boy" route, while the elder brother takes the path which is much more difficult to sniff out. He represents the religious person -the person who prays, lives morally, and tries really hard to be good so that God will be like a cosmic Santa Claus. "If I try really hard, God will help me out." "If I be good, God will love me and bless me with the things I want." Another similar approach is like this: "If I apply Biblical principles, I can get a happy and harmonious life." God, in either case, is there superficially at best or for spiritual business transactions to get the life we want for ourselves.
The second thing we see, both from the Bible and painfully from experience, is that we cannot overcome the flesh by our own resources. We can't change ourselves. We are the Israelites, living in slavery, captive to an enemy more powerful than we can overcome.
This flies in the face of everything borne out of religion, even with the label "Christian" on it, but it makes perfect sense. You can't use flesh to overcome flesh. You can't use your own resources to overcome that part of you that is hell-bent on using your own resources to carve out and manage your life apart from God.
I remember conversations I've had with a dear friend of mine who beat upon himself and obsessed about killing some particular sin in his life. He would go through periods where the various mechanisms and "spiritual disciplines" in his life seemed to "work" -he had momentary success. But then stressful circumstances would come along or, out of nowhere, he would fall flat on his face. The result was despair. Why? Partly because despair is the result of relying upon our own efforts and then finding our we are still just as helpless as the day before. It is a mixture of hopelessness and self-pity.
It is easy to forget this point. It is easy to resort to flesh to seek to accomplish very Christian-looking goals. One of the most common ones is to kill off a particularly bothersome sin. But if we look a bit more closely at why we endeavor so strongly to clean ourselves up, using the Bible and seeking to leverage God somehow through our own efforts, we often find things like... we just want to avoid pain... we just want to avoid the public embarassment of our sin (pride)... we want to be able to boast in our spiritual progress and maturity... we want to avoid discomfort... or we may even, if we are honest, want to avoid God's anger -we may be fueled completely by fear of punishment. On some level, there isn't much wrong with wanting these things, but sometimes these make up the driving force for our self-effort. All told, if you look at them honestly they are pretty self-interested. "I need to stop this sin so that I can get my life to be how I want."
The Gospel reminds us that the flesh is not something we can overcome ourselves. Jesus died to pay for our sins and rise from the grave in newness of life, conquering Satan, sin, and death. He had to do it -not just for our forgiveness but for our sanctification, for our conformity into His image, for us to have newness of life in Him by His Spirit. This does not mean we are inactive in our sanctification at all. However, it means that our life in Christ, growing in grace, is a life of surrendered dependence on the Spirit of God to accomplish what God promised to complete in us. Our action takes on a posture of dependence and life-abandonment over and over.
The last thing I want to comment on is that the antithesis of the flesh is the Spirit, or, for our purposes, grace. The thing about grace is that it only makes sense and has any value to someone who has come to the end of the rope with their flesh. They see the destructiveness and futility of their flesh, and under the conviction of the Holy Spirit, they see how walking in the flesh, even in the most pious and religious of forms, is truly contending against God.
Grace comes along and says, "Though you have walked your own way, I still come to you, I still love you, and I give up Myself to make you Mine, not because of anything you can do, and give you the power to be transformed into what I want for you." Grace is about receiving as a gift what you could never earn. The flesh, as we recall, is all about what I can get for myself through my own efforts. Grace is also about restoration to God. The flesh is about getting God's things apart from God. See the clash? This is why they do not mix.
Paul outlines this in his letter to the Galatians. He uses the example of the two sons born to Abraham -Ishmael, born of Hagar, the servant-girl; and Isaac, born of Sarah, his wife. If you recall, God promised Abraham that he and his wife would have a son, and he would be the father of many nations. The idea was preposterous. His wife was well past child-rearing age. They were elderly. Years went by and nothing happened, so what did they do? They came up with a plan to do it out of their own resources. Hagar, Sarah's servant, was given to Abraham to bear him a son, and she did. Ishmael was born. Over a decade later, lo and behold Sarah became pregnant by Abraham and Isaac was born. Woops.
Paul's point is this: you can't mix the flesh and grace. They are two completely different animals. One is by human effort and the other is by God's promise, through grace. You don't earn a promise. You can't make a promise happen by taking control and trying to produce the same results through your own resources. God simply promises it, and it comes to pass. Grace. Gratis.