God's specific will (from a recent e-mail)

Question, how do you know that God really wants you to go to Africa? Could this be a test of your faith?
I'm certain this is a test of our faith. God is deeply interested in our faith.
We know that God wants us to go to Mali because He has opened doors in that directions, and, more importantly, it is the greatest desire of our hearts. The Bible is rife with the command to go, make Him known, proclaim His works, and glorify His Son. Heidi's and my hearts resonate with going. It's one of those things that is so ingrained in us that it's a little hard to understand how everyone else isn't completely leveled with the wonderful and adventurous task set before us. The ways that Heidi's and my desires match is a confirmation for us. At this point, I would go to my grave trying to reach Mali. Admittedly our inability is frustrating. We don't understand exactly why God is leading us down the scenic route, but we're confident it is for His greatest glory, just like a missionary we know that took him nearly 20 years to get where God was leading him. That struggle now defines his as separate from this world, unique in his pursuit of God (or more accurately, God's pursuit of him).