God's calling to missions is not authoritative the way the Scriptures are. Your calling is never beyond question. You can't claim it to others the way you quote Scripture to them.
Nevertheless our calling can be profoundly and durably sure in our own heart. It is the work of God to bring our heart to a point of conviction that, all things considered-including Scripture-this path is the path of obedience. The conviction is not infallible. But when it is of God, it brings peace.
How does God waken such a calling? I will suggest ten means that he uses. Only one of these is infallible-the Bible. All the others are relative. They are not absolutely decisive in your leading. They are important. But any of them can be overridden by the others. Various combinations of these are the fuel God uses to drive the engine of his calling in your life.
1. Above all, know your Bible and saturate your mind with it.
The Bible shapes our minds for mission durability (Psalm 1:1-3), and makes us burn for Christ (Luke 24:32).
2. Know your gifts and know yourself.
Every Christian has gifts (1 Peter 4:10-11). Knowing them shapes your convictions about your calling. And knowing yourself (as Paul exemplifies in Romans 7:15-24) deepens your sense of fitness for various ministries. (Keep in mind that this can be overridden by other facts!)
3. Ponder the need of the world.
