Commentary. Living sacrifice. Kazark
1 Therefore, I urge you, brothers and sisters, in view of God’s mercy, to offer your bodies as a living sacrifice, holy and pleasing to God—this is your true and proper worship.
Rom 12:1 (NIV)
This verse is the beginning of Paul's call to a holy life (imperative) on the basis of the rich Gospel he has presented (the indicative: justification, regeneration, sanctification...). And Paul, as is typical of the organization and care of his thought and especially of Romans, gives this verse and a summary or thesis statement of everything which he is going to say during the imperative part of the letter.
I would render the verse something like this:
So I urge you, brothers, because of the mercy of God, to present your bodies as a living sacrifice, holy and pleasing to God, your spiritual/reasonable worship.
Possible reasons for using the term sacrifice:
• Those who are in Christ imitate Christ and share his sufferings in this life. While our sacrifice is not redemptive (in the place of another), yet it is to be for another, as was his.
The sigma in the participle ζῶσαν is because it is feminine, not because it is aorist. It is a present participle and as such has a continuous aspect just like the English participle living. "The living sacrifice stands in contrast to those which were killed and refers to a constant dedication" (The New Linguistic and Exegetical Key to the Greek New Testament).
This is λογικός, referring to the human spirit, not the more typical πνευματικός, which refers usually to the Spirit of God and sometimes to evil spirits. The precise meaning of it in this context is disputed (thus the NIV rendering "true and proper"), but I think at the very least it serves as a contrast to "bodies" — yes, we are to offer our bodies, but such a sacrifice is not to be thought of in a merely external way.
Paul is commanding us to totally give ourselves up to God. As Paul Washer points out in a number of his sermons, he does not here mean to restrict the command to our bodies. Rather, lest we make holiness something which is ephemeral, he gives us a concrete embodiment of the command to holiness. This is our true and proper worship because the old system of bulls and goats has passed away, and because true worship to God is a holistic action of the man. God asks for total, not partial, devotion—body and soul. Once again, though, even the fact that he would urge them to offer indicates that the command is addressed to a human soul and thus a total devotion is in view.