Other than your Bible, a basic tool to take believers' concern for the world's lost to the next level--as well as impact those lost people through prayer, is Operation World, the Definitive Prayer Guide to Every Nation. Released a year ago, Jason Mandryk's 7th edition is a gold mine of info about the world's nations, its people groups, their religions, the gospel work that is or isn't going on among them, and what to pray for. Which is where we come in. You may not be called to Craigslist all your stuff for an airline ticket to a dot on a map where there's an unreached people group and no cell service. But you are called to be involved in getting Christians to that spot, keeping them there, and interceding for their success. When God saved us, we all became enlistees to serve Christ in His mission of building and expanding His kingdom. Prayer is a contribution everybody can make to that effort. The book will set you back about $13.50 at CBD and under $13 at Amazon.
Just watch out. It has been proven time and time again that believers who pray for other people often are moved to get involved in some way with those same people. You might end up spending money, time, or something else on their behalf.
Representative of this are founders of the e3 Partners mission organization, Tom and JoAnn Doyle. "Operation World changed our lives! In 1999, my wife and I began praying for a country each night in Operation World. God opened our hearts wide for lost people, especially in the Middle East. Every night as we would read about Iran, Israel and other nations, our hearts were gripped with the need to reach these countries for Christ. Within two years, God called us to leave senior pastoring a local church in the Colorado Springs area, and to go to the very places that we had been praying for! So as you pray through Operation World, just remember, God may radically change your world to reach His world."