He has planted eternity in the human heart. Eccl. 3:11 NLT
And He has made from one blood every nation of men to dwell on all the face of the earth, and has determined their preappointed times and the boundaries of their dwellings, 27 so that they should seek the Lord, in the hope that they might grope for Him and find Him, though He is not far from each one of us; 28 for in Him we live and move and have our being, as also some of your own poets have said, ‘For we are also His offspring.’ Acts 17:26-28 NLT
Humans are different from animals in that we can ponder our purpose. We have the capability to act so as to satisfy ourselves -- our needs and drives. But 3:11 points out that we also can perceive that there is more to life than we can experience. God made us with a vacancy in us that only He can fill. Like moles tunneling upward, we paw our way toward the daylight, but can't see too well just what God has planned, as Acts 17 states. Note how earlier societies built physical gods. Creation reveals god's existence, but Christ and the Bible reveal what is really going on, spiritually speaking.
As Don Richardson states in his book Eternity in Their Hearts, God has prepared societies for the Gospel. They have perceived that someone not "under the sun" exists, and have plugged this perception into their culture, so that when the Gospel arrives, it connects to that plug, like two electrical plugs coming together, with one connected to a power source. Thus, the eternal longing can be satisfied.
We who believe thank God that we have been graced with eternal truth, and need to consider those who have yet to receive that grace.
Steven Curtis Chapman - More To This Life [live]