Christ Encourages Paul
Paul is very experienced in persecution; again and again he has been forced out of a city because of violent opposition. Here in Corinth he has had a mixed reception: opposition and blasphemy have led him to shake the dust of his feet off against the Jews - and yet there have also been encouragements, with some notable conversions. Should he stay or should he move on?
And at this point the Lord speaks to Paul in a vision, exhorting him to stay - not to fear but to speak; and promising to be with him.
Here is much-needed encouragement. The Lord knew that Paul needed it after so much persecution. We serve one who knows how to encourage.
Ordinarily God's will for us is to carry on in the things that we're doing. We don't therefore interpret troubles as signals to stop but look for encouragement to Christ and keep on keeping on.