Prayer is the walkie-talkie on the battlefield of the world. It calls in for the accurate location of the target of the Word. It calls in to ask for the protection of air cover. It calls in to ask for fire power to blast open a way for the tanks of the Word of God. It calls in the miracle of healing for the wounded soldiers. It calls in supplies for the forces. And it calls in the needed reinforcements.
John Piper
Website: https://www.desiringgod.org/messages/prayer-the-work-of-missions