The emphasis is on what is being expressed. Once you step into Christianity you are to die to everything and live only by Christ. So what is being expressed, is it Christ or is it yourself? Well, you can say you are expressing righteousness, but is that righteousness Christ, or are you just expressing your own concept of righteousness. You see, we get so caught up preaching concepts, "you must be righteous, you must be holy, you must be humble..." but the truth is that we are only after our own worldview, our own self. We preach what we think humility is, and we want people to express that.
No, God would not have that, Christ is the only acceptable sacrifice; you either present Christ to Him or go home. God wants to see Christ expressed and nothing else. If you won't give Him Christ then there is no need of you being a Christian. This Christ can be expressed in many ways, but what matters is that he is the one being expressed. God doesn't care, all He wants to see is Christ being expressed; the God who is spirit manifesting in the flesh.
You do not act out Christ, you manifest him. What some Christians try to do is look at the Bible, look at Jesus and try to act him out. No, that is not expressing Christ, that is acting. We are to live not act, live by the Life (Christ). Let Jesus himself be the one pouring out from the spirit into your flesh, finding expression in this mortal body. Let him manifest himself, let him walk the earth through you. All that God desire is to find expression through this flesh.
This is an excerpt from my book Christ: The Christian Spirituality