I cannot shake the sense that I should go overseas, but I do not trust my own motives. How do I test whether this is really God?

“Also I heard the voice of the Lord, saying, Whom shall I send, and who will go for us? Then said I, Here am I; send me.”

Isaiah's vision in the temple comes in the year a king died, a moment of national uncertainty. Before he volunteers for anything, he has seen God's holiness, recognised his own unfitness, and been cleansed. The order matters: willingness comes after the encounter rather than out of enthusiasm or a taste for adventure. His sending also arrived with a warning that very few would listen to him.

“And a vision appeared to Paul in the night; There stood a man of Macedonia, and prayed him, saying, Come over into Macedonia, and help us. And after he had seen the vision, immediately we endeavoured to go into Macedonia, assuredly gathering that the Lord had called us for to preach the gospel unto them.”

Luke records Paul's team being blocked twice from where they intended to go, and only then receiving a night vision of a man from Macedonia. Notice how the crew respond: they conclude together, weighing what had happened, rather than one person announcing it to the rest. Guidance here is corporate, gradual, and partly made out of closed doors.