I’m working through Romans with the help of Douglas Moo. Moo does a great job of unpacking the importance of Paul’s phrase, “the obedience of faith” (Rom 1:5). He argues that “the obedience of faith” captures the full dimension of Paul’s apostolic task. Paul was not just an evangelist making converts, he was an apostle making disciples and forming communities.
The obedience of faith is the goal of Paul’s apostolic task. A lot of people are running around these days using the term “apostolic,” a term that is functionally equivalent to “missional”. It means different things to different people. How does Paul use the term? According to Moo,
Paul saw his task as calling men and women to submission to the lordship of Christ (Rom 1:4b and 7b), a submission that began with conversion but which was to continue in a deepening, lifelong commitment.
The obedience of faith begins and ends with submission to the Lordship of Christ. You can’t have the kingdom without the King.
Obedience alone is just another form of legalism. Paul works for “the obedience of faith” among people who were far from God. Moo again,
This obedience to Christ as Lord is always closely related to faith, both as an initial, decisive step of faith and as a continuing "faith" relationship with Christ. In light of this, we understand the words "obedience" and "faith" to be mutually interpreting: obedience always involves faith, and faith always involves obedience. They should not be equated, compartmentalized, or made into separate stages of Christian experience.
The obedience of faith is not a second level of Christian experience post conversion. You can’t separate faith and obedience, obedience and faith.
Paul called men and women to a faith that was always inseparable from obedience — for the Savior in whom we believe is nothing less than our Lord — and to an obedience that could never be divorced from faith — for we can obey Jesus as Lord only when we have given ourselves to him in faith.
Evangelists might feel that their work is done when someone believes. Not an apostle. Paul won individuals to faith in Christ, then he always formed them into disciple-making communities. No discipleship without church formation.
Viewed in this light, the phrase captures the full dimension of Paul's apostolic task, a task that was not confined to initial evangelization but that included also the building up and firm establishment of churches.