12:1 therefore. “Therefore,” that is, in view of all the great doctrinal truths expounded in Romans 1–11, we should live as described in Romans 12–16. As is true in most of Paul’s epistles, he first lays the doctrinal foundation, then draws out the practical consequences.
12:1 living sacrifice. The key to real Christian living is dying to the world and living unto Christ. This great theme appears repeatedly throughout the New Testament.
12:1 reasonable service. “Reasonable” is the Greek logikos, from which we derive our word “logical,” and “service” is the Greek latreian, referring to service as a priest. We have been made “an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ” (I Peter 2:5), and it is perfectly logical that we render such lifelong service.