Even when we were dead in our trespasses, [God] made us alive together with
Christ — by grace you have been saved.” (Ephesians 2:5)

The great missionary hope is that when the gospel is preached in the power of
the Holy Spirit, God himself does what man cannot do — he creates the faith
that saves. The call of God does what the call of man can’t. It raises the
dead. It creates spiritual life. It is like the call of Jesus to Lazarus in
the tomb, “Come forth!” (John 11:43).

We can waken someone from sleep with our call, but God’s call can summon into
being things that are not (Romans 4:17). God’s call is irresistible in the
sense that it can overcome all resistance. It is infallibly effective
according to God’s purpose — so much so that Paul can say, “Those whom [God]
called he also justified” (Romans 8:30).

In other words, God’s call is so effectual that it infallibly creates the
faith through which a person is justified. All the called are justified. But
none is justified without faith (Romans 5:1). So the call of God cannot fail
in its intended effect. It irresistibly secures the faith that justifies.

This is what man cannot do. It is impossible. Only God can take out the heart
of stone (Ezekiel 36:26). Only God can draw people to the Son (John 6:44, 65).
Only God can open the heart so that it gives heed to the gospel (Acts 16:14).
Only the Good Shepherd knows his sheep by name.

He calls them and they follow (John 10:3–4, 14). The sovereign grace of God,
doing the humanly impossible, is the great missionary hope.