Sin in the Life of a Believer

What is the role of sin in the life of a believer? I know that believers are free from the eternal consequences but sometimes I wish I was free from all of the power of sin here and now. To what extent can that really happen? Namely, what kind of temporal freedom from sin can the believer hope for on earth? I guess I have just been convicted by some passages in 1 John that speak of believers continuing on in sin. John says that those who walk in the light won't continue in sin and I just can't quite figure out how he means it. At first glance one would think that John actually means that once you become a Christian you never actually sin again, but that can't be it right? If that is what he means then I guess I'm not really a believer...except that I know I have the Holy Spirit inside of me who testifies to my status. So how do I reconcile the fact that I'm a believer and yet still sin?