It feels like something mysterious happened to me when I turned 40. It's like the blinders that I had been wearing my whole life started falling off and I started slowly realizing who I really was as a person.....and it wasn't good! In the process somewhere I ran across some of Martin Luther's writings and they really seemed to hit home to me. I just recently watched a Netflix documentary about his life and it brought up the term 'Incurvatus in se' and it really has hit home to me. Here's the definition from wikipedia. "A theological phrase describing a life lived "inward" for oneself rather than "outward" for God and others."
Luther used the term in describing our state as sinners saying that 'man as so curved in upon himself that he uses not only physical but even spiritual goods for his own purposes and in all things seeks only himself'. Now I can hear everyone say, 'right on, preach it brother, that's exactly how I was before I was saved". But here's where my 40 year old realization kicks in, it's not that this is how I was before I was saved....it's how I still am. My sinful nature didn't stop at salvation, it's still there. I can't look into your heart, but I can tell you that I know the I'm saved by the blood of Jesus and I can tell you that still my heart is not right. I can put on the Christian face at church and say the right things and pray and get up in the mornings to study scripture, but I can't escape my nature on this earth. It comes in conversations with my wife about how, "I would help them but they kind of brought it on themselves". It even comes in my prayer time. How many of my prayers have been for self seeking purposes and how very few of them have been for God's glory and for the love of others. Even when I seemingly do things I ought to do many of them are motivated by me trying to be a good Christian or seek some type of favor from God from doing the right thing. I want God to look at me and say, 'now there's a man after my own heart' so even my seeking to do good comes from a desire to benefit myself in some way.
So what's the answer? Try harder? Pray more? Sure, the more of the spirit we feed the less the flesh has control of us. I've seen that in my life personally. But still, how do you even make yourself want to try harder? It's interesting what Luther says the answer to this realization is. He says that the only meaningful response to the realization of Incurvatus in se is that of the tax collector who 'would not even look up to heaven, but was beating his breast and saying ‘God, be merciful to me, a sinner!'.
I think I agree with Luther that the depravity of our hearts is not our issue to fix. Man does not have the power to fix his sin. All we can do is realize our sin and beg for mercy. As God sanctifies us hopefully our flesh will be less and less in control of us and the Spirit will guide our steps. But the flesh is still there and can not be shed in this life. Sometimes I think that God left it there on purpose so we can be reminded often of what His grace has truly done for us.
Lastly, many look at Paul's "thorn in the flesh" as a physical ailment that he had. I do not believe that to be true. I think it's a sin problem that he battled daily (lust, pride, etc.) and think he sometimes lost that battle with the flesh. I think he was asking God to remove his vice from him and make that temptation no longer tempting to him. If I'm right, look at God's answer. He said, "No, my grace is sufficient for you". I've had a herniated disk in my back and trust me when I say that God's grace was no comfort to the agonizing pain. But, when I fall into sin and feel like I'm not even a Christian because of what I said or did and come to God and ask for his help and hear him say, "Out of my grace I've died on the cross for your failures and that grace is sufficient for your sin" I tell you, it makes me want to praise Him all the more! How wonderful our God is that he would save a sinner like me. He didn't just save the sinner that I used to be, He also saved the sinner that I am.