Another vision quieted Paul"s fears (cf. Acts 23:11; Acts 27:23-24). His ministry in Corinth was getting off to a rough start, as many ministries do, but it would succeed. He needed encouragement to be courageous and to keep speaking rather than falling silent. The Lord could see His elect in Corinth before their conversions even though Paul could not. [source][source][source]
"Please note that divine sovereignty in election is not a deterrent to human responsibility in evangelism. Quite the opposite is true! Divine election is one of the greatest encouragements to the preaching of the Gospel. Because Paul knew that God already had people set apart for salvation, he stayed where he was and preached the Gospel with faith and courage. Paul"s responsibility was to obey the commission; God"s responsibility was to save sinners." [1][source]