I've been told many, many times that one of the key virtues of a Christian life is repentance. That is, turning away from sin and towards God: daily, hourly, minute-ly, etc. This make sense. At least, it makes sense if we believe ourselves to be so embroiled in sin, post-justification, post-start-of-sanctification, post-salvation (at least the beginning parts of it), that we cannot exist without sinning. In that case, a life of repentance is utterly necessary and utterly impossible (and not only from man's standpoint, but also God's, since He was unable to break sin's yoke over you either at the Cross or at the "moment" of faith -- but that is another story for another day: I'm hoping to *eventually* publish an article about this theological snafu).
But...what if, when we are brought into a right relationship with God (whether you want to call that salvation or justification or just plain bliss), the stranglehold of sin is broken and we can, theoretically, live without sin's domineering presence in our lives? I'm not arguing for perfectionism, that is, a human's ability to totally conquer sin this side of the general resurrection so that there is no spiritual or moral struggle. I am arguing for a Christian's power to conquer temptation and sin through great striving in the Spirit (for starters, it takes "praying without ceasing" -- something very few have been able to accomplish), a striving that, if Ephesians 5 is to be believed, will continue on with us until the time of our mortal demise: that is, we have changed sides in the cosmic war, but that doesn't mean the war is over. Rather, the war, for us, is now just begun, or at least our part in it.
And one of the things that happens is that sin, even though its power has been effectively broken by the Cross, still calls to us. To change sides, to change allegiances (that is, to change pistis, faith), and to come back over. A life of repentance, then, is one in which we recognize which side we are on and stay put.
I find this martial imagery to be very illuminating, especially when counseling students. Many, and this once included myself, belived that once you sinned, you are, effectively, out of the family. You are condemned where you stand. For some, this means that any sin constitutes a need for a "new" salvation, since the old one has been irrevocably lost. However, if you are shot at during a war, that doesn't mean you work for the enemy. If, once you've been shot at, you have a change of heart and realize that the other side is "in the right" and you defect, then, yes, you do work for the other side. There is a technical theological term for this: apostasy. This is what is condemned, for example, in Hebrews 6. Being shot at, though, or even taking a hit and falling down, or not carrying through an order ("transgressing the command," as it were), does not constitute apostasy. Just sin. Something to avoid next time, to ask the Commander for clarification, for help, for assistance, for (sometimes) reassignment. Sometimes, alas, the shots wound us deep, shrapnel cuts and we wonder why we must live with this (I have students who struggle, valiantly, with same-sex attraction: I often think this might be a helpful heuristic category, but I'd have to ask them first): but this is not apostasy -- it is possible to be a faithful soldier and struggle with some deep wound.
Strangely, or maybe not, this isn't what I originally set out to write. I wanted to write about how death is what we repent from, that is, from the lifestyle and works of death, which characterize the old world, the old self. This is what produces sin in us, but something else came out. At any rate, may it be to the glory of God and may He forgive me where I've misstepped.