'I appeal to you, brothers, by our Lord Jesus Christ and by the love of the Spirit, to strive together with me in your prayers to God on my behalf.' Romans 15:30
James 5:16 says that, 'the prayer of a righteous person has great power as it is working.' God is faithful and just. He hears our prayers and is at work in each of our lives. Even if we cannot personally reach every person throughout the nations, He can. We can pray for their hearts to be stirred. We can pray for a revival among the unreached people groups. We can trust and know that God is sovereign and that He hears our prayers.
John Piper said, "Prayer is primarily a wartime walkie-talkie for the mission of the church as it advances against the powers of darkness and unbelief. It is not surprising that prayer malfunctions when we try to make it a domestic intercom to call upstairs for more comforts in the den. Until you know that life is war, you cannot know what prayer is for: Prayer is for the accomplishment of a wartime mission."