Taken in context, the chapter is a picture of holiness. It pictures not only the moral things that followers of God are to do or refrain from, but behaviors that don't have a distinctly moral component, like wearing mixed fibers, are intended to illustrate holiness as being "set apart."
The people of God are supposed to stand out in society, and not just by dressing or wearing our hair differently. Our behavior is supposed to make others take notice, in a good way. Although as Christians, Christ is the fulfillment of the law and has paid the penalty for our sin, this notion of living holy lives has not changed.
In recognition and thanksgiving for what Jesus has done, we are to live lives set apart, different from the society in which we live. Our lives should be characterized by generosity (v. 9), integrity (v.10), honesty (v. 13), kindness (v. 14), justice (v. 15), love (v. 17), and purity (v.20).