1 Corinthians 16:9

For a great door and effectual is opened unto me, and there are many adversaries (KJV)

Then: This remark explains Paul's reasoning. He wants to travel soon because mission opportunities abound, and always concerned about enemies to the gospel news, he probably sees signs that it might be time for him to move on. Some commentators like Wright, mark this as an end to one topic in Paul's letter; others, like Baker, include thoughts about Paul's fellow workers, so continue on through verse twelve.

Now: We need to be awake to area needs for teaching the gospel. We also need to pray for the doors, pray for the doors to open and pray for ability to make effectual use of the open doors. Adversaries can be human or caused by events. Sometimes laws bar particular ministries and sometimes funding is lacking. Whatever the impediment, the Holy Spirit directs and guides while reminding believers of Paul's words, "All things work together for good even to them that are called according to his purpose" (Romans 8:28).