'One of Those Difficult to Answer Questions'

Romans 7:17-19

¹⁷ As it is, it is no longer I myself who do it, but it is sin living in me. ¹⁸ For I know that good itself does not dwell in me, that is, in my sinful nature.^[a] For I have the desire to do what is good, but I cannot carry it out. ¹⁹ For I do not do the good I want to do, but the evil I do not want to do—this I keep on doing."


Here is a question I can't seem to answer...God gives us the Holy Spirit at baptism. The Holy Spirit lives within us. Because of God's grace, we become a holy nation. Yet, we have a sinful nature and are full of sin. God sees us as pure and blameless and we are called new creations and his righteousness, yet my heart is deceitful and beyond cure....God left Jesus at the time of his death on the cross because he was full of sin, and he never mixes with sin except, apparently in the case of each of us as human beings. I don't get it....A lot of this just doesn't make sense...Is my theology completely messed up, or is this just one of those things that is not to be understood? I am told I am forgiven, yet I am also told that I am utterly sinful, poor, blind and naked...I always struggle with this concept because it doesn't make sense. I am told that my heart is inherently bad, yet I am created in the image of God.  Huh? How can I be a new creation in Christ, but be so sinful that I can't trust even myself. I don't know how to rectify this in my heart. Unless I go this route....
Here is my take on the answer...
I believe that what the Bible says is true on both fronts, but that there is a distinction to be made. Our hearts are deceitful and beyond cure, until God comes along. We are utterly sinful and unrighteous, until that magical baptism that ushers in the power of the Holy Spirit. We are poor, blind, naked, and lost, until that rebirth, coupled with repentance and faith in God, that allows us to be transformed into a new creation. My heart is inherently bad, but once God saved me, my heart was made new. We are given a heart of flesh to replace our heart of stone. It now makes perfect sense. I could give up on the quest, give up on my relationship with God, allow my old nature to take control, and lose my salvation..but why would I do that??? Why do people do that??? (Another topic altogether)...The part I always get hung up on is the existence of the sinful nature....Where does it live? Does it live in my heart where the Holy Spirit lives? Does my nature just mean 'tendencies' I have apart from the Lord? Dictionary.com gives the following definition for nature: 'the instincts or inherent tendencies directing conduct: a man of good nature.' Ahhh-hah!! Tendencies...I lived 20 years outside of God and his Kingdom and I was often left to my own devices...I learned to act on the temptations of Satan and I ended up, through many years of practice, as one who tended towards sin. I wasn't sinful at birth, but I was born into a spiritual war for my soul, and since I wasn't in a God-fearing household, I was doomed from the beginning. But then God came near, sent some faithful saints to intercept me and teach me the ways of Christ. This has to be the answer, right? But if it is, what are the implications? Do I teach the right message? Do I believe the right things? Overall, I would say 'Yes'...but what do I believe in my heart? I spend more time defeated than I do redeemed. I live more in the past than I do in eternity. I focus so much on what I once was, that I miss out on who I am and who I am becoming. I consider myself a sinner more than a saint...it can't be true though...except maybe in the sense of how alcoholics say they are still alcoholics but are reformed...Maybe that's it! I am a reformed sinner. A saint with a nasty tendency towards sin. It makes much more sense now...but am I just making stuff up? It seems to be true and the Bible seems to support this thought, but then why do we focus so much on what we need to repent of? Shouldn't it be more about what I need to add to my heart to sway my tendencies towards goodness and righteousness? 
I know it's a lot to ponder, but it's one of those things that has always been a question of my soul. Share your thoughts...I'd love to here where you come in...