Ecclesiastes 3:11 (NKJV)
He has made everything beautiful in its time. Also He has put eternity in their hearts, except that no one can find out the work that God does from beginning to end.
Blaise Pascal, the French philosopher and mathematician once said "Within each one of us there is a God-shaped vacuum that only God can fill." That is to say, only God can truly satisfy the deep longings and needs of man. God has wired us this way. Don Richardson, who wrote the book of the same name as the title of this post, shows that there is remnant evidence of once held belief in the one true God among all cultures. Combining the deep needs common to all men for a redeeming God along with these cultural connections to the truth it is plain to see how the commission to evangelize the world is not only possible but that the road is already paved.
Lest we become too proud of our scientific understanding of how the world works, this verse also reminds us that we'll never know it all.