The writer of Ecclesiastes says:
Ecclesiastes 12:13-14 ¶ Now all has been heard; here is the conclusion of the matter: Fear God and keep his commandments, for this is the whole duty of man. For God will bring every deed into judgment, including every hidden thing, whether it is good or evil.
If the whole duty of man is to fear God and follow His commandments, then I suppose, my Christian interpretation of the purpose of life would be to learn that. The purpose of life, therefore, could be summed up by saying we are here to learn about God and have a relationship with Him (could it be that simple?).
God, therefore, designed us, life on planet earth, and for that matter, the universe, to be conducive to learning about Him.
Romans 1:20 For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse.
Psalm 19:1 The heavens declare the glory of God; the skies proclaim the work of his hands. Day after day they pour forth speech; night after night they display knowledge. There is no speech or language where their voice is not heard.
So right off the bat, you are confronted with a mind boggling universe and an innate understanding that this was no accident. The stage is set, God exists.
As you observe life, as you live life, you begin to understand that those living are not in complete control of their destiny. In the world around you, you see mortality. At the same time, man does not see death as finality because God has set eternity into the hearts of men (Ecclesiastes 3:11). This understanding lends itself to the beginning of wisdom, the fear of God (Proverbs 9:10). After all, we are going to have to give an answer for the things we’ve done while in the body (2 Corinthians 5:10). This fear of God can motivate us to learn what we can about God, and potentially, come to the knowledge of Christ and a real relationship with God. And so it goes.