courtesy of Wikipedia
Mormon also spoke of "how great" the "nothingness of man" is. That's interesting, that nothingness can be relatively large. You can have different levels of nothingness! This clarifies the above point about how not having charity leads to being nothing. The less charity you have, the less you "exist" in some sense. Which actually fits with our intuition: we think of the least charitable people as missing a part of their heart, or incomplete in some way. They're not all there.
Charity, then, is an existential need. If we were to become entirely devoid of charity, we would suffer the eternal destruction of both soul and body. Conversely, the more we cleave unto charity and are filled with it, the more we find ourselves, the more we exist, the more perfect (read: complete) and divine we are. It's a spectrum from nothingness to Godliness.
God is brimming with charity, so he exists in the fullest sense of the word. His light, which is intimately intertwined with his charity, actually emanates into all things, providing them with life. This is why he wants to fill us with his love, why he commands us to be full of love/charity. This is the same promise that as we become Gods we shall receive all that the Father has.
We already have a portion of God's love within us. We know this because we exist. If we would continue to exist, and to achieve abundant eternal lives, we need charity. Charity never faileth. We, with charity, will never die.