Who am I: I evolved from rocks, billions and billions of years ago (used to be million and million of years but they needed a little more time)
Why am I here: No purpose to life because we came from dirt which came from nothing.
What do I do while I am here: Whatever the hell I want because I answer to nobody
What happens when I die: I become worm food and rot in the grave.
The Christians point of view
Who am I: A creation of God, His workmanship created in His image.
Why am I here: To love and fellowship with God and His creation
What do I do while I am here: Walk in the Spirit of God: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control
What happens when I die: Spend eternity in heaven with God and His people.