Romans 15:14-21
Chapter 15
However, I have written boldly at some points in this letter to remind you of what you already know. I do this in accordance with the grace that God has given me
when I was sent to the pagan nations. I dedicated myself to serving the Good News of God as a minister of Christ Jesus, aiming to present the non-Jews to God as an acceptable offering, consecrated by the Holy Spirit.
This service of God is a source of pride for me, in Christ Jesus.
Of course, I would not dare to speak of other things, but what Christ himself has done through me—my words and my works,
with miracles and signs—by the power of the Holy Spirit—so that non-Jews may obey the faith. In this way, I have extended the Good News to all parts, from Jerusalem to Illyricum.
I have been very careful, and I am proud of this, not to preach in places where Christ is already known, nor to build upon foundations laid by others.
Let it be as scripture says: Those who have not been told about him will see, and those who have not heard will understand.

Commentaries
Paul’s Mission to the Gentiles.
These lines seem to suggest that Paul wants to excuse his intrusion into a Church he did not establish and thus justify his planned visit. The language is courteous and restrained. The letter, the Apostle appears to say, is not meant to evangelize the faithful Christians of Rome, but merely to refresh what is already known.
Paul neither apologizes for the letter he is writing nor for the visit he is announcing. The Christians in Rome likely saw both of the Apostles’ actions as entirely natural. Would the same be true today if a bishop sent a similar letter to Christians in another diocese? In the early centuries, shared responsibility and collegiality among the churches created the typical environment in which leaders of different Christian communities worked.