We will never be completely free of sin while we are on this earth, Although Jesus Christ came to live within us by His Spirit when we gave our lives to Him, our old sinful nature still resides within us, and as long as we live it will keep trying to rear it ugly self.
But that must not keep us from pursuing perfection! To put it another way, that must keep us from battling sin and embracing righteousness. God's will is that we would become more like Christ- more like Him in our purity, our love, our service.
" Not that I have already attained, or am already perfected; but I press on, that I may lay hold of that for which Christ Jesus has also laid hold of me. Brethren, I do not count myself to have apprehended; but one thing I do, forgetting those things which are behind and reaching forward to those things which are ahead, "Philippians 3:12-13 (NKJV)