"..that you, being rooted and grounded in love, may be able to comprehend with all the saints what is the breadth and length and height and depth, and to know the love of Christ which surpasses knowledge, that you may be filled up to all the fullness of God." Ephesians 3:17b-19 (NASB, emphasis mine)
Isn't it amazing that God has given us knowledge of something we can't even grasp? Like the concept of fullness: God has given us the desire for it, the ability to perceive it, even a name for it. But true fullness in life is being completely filled with God - something we never can really know in its entirety until we get to heaven.
Even Christians, who do experience a measure of the fullness of Christ now, cannot perfectly be filled with Him until we have our heavenly bodies - without sin or desire of sin.
Doesn't it make you long for that day, when that emptiness that all mankind aches with will finally be filled for those who are in Christ? And doesn't it make you long to tell others so that they too might have the sure hope of true fulfillment?