And that men may be brought to believe, God mercifully sends the messengers of these most joyful tidings to whom He will and at what time He pleases; by whose ministry men are called to repentance and faith in Christ crucified. How then shall they call on him in whom they have not believed? And how shall they believe in him whom they have not heard? And how shall they hear without a preacher? And how shall they preach except they be sent? (Rom.10:14, 15).