Mormons have a fascinating view about the purpose of life. They believe that before we were born, we all lived with God as one big family. Since God wanted his children to experience the kind of happiness and joy he had achieved as a glorious Father, one day he got his children all together and told them of his grand desire.
Naturally, everybody got excited. But then he told them, "I just can't give that joy and happiness I have to you, my children. You need to understand it for yourselves first and learn to appreciate it." He then told them that they needed to be on their own first so that they could experience happiness - and its opposite. They also needed to be tested to see if they can believe in these things even if they weren't in His presence.
"And when you understand it fully," God continued, "then you can come back and live again with me and really feel happy when I share with you my glory." And that's why everybody's here on earth, to know true happiness and claim it forever.