brothers: The Greek word adelphoi describes people who are in a family relationship. Paul and other New Testament writers use this word to show that Christians belong to one family because they are united in Christ. The word refers to both male and female Christians.
but have been prevented from visiting until now: Paul wrote this letter while in Corinth near the end of his third missionary journey (see Acts 20:2–4; compare Romans 16:21–23). Paul had been busy planting and supporting churches in the eastern Mediterranean. Before visiting the Roman Christians, he needed to return to Jerusalem to deliver money collected from the Gentile (non-Jewish) churches for the poor Jewish Christians (15:23–29).