Agreed that this song could be about God or a lover.
Being deeply in love right now, I can counter some points that wayoflife made on the last page. Your lover can calm storms. Inner storms. They can make you at ease, bring you peace. I don't need Jesus to know what my lover makes me feel is true. And I don't need Jesus to know what peace or love is. Right now, my lover is the shining light of my life. He has the ability to make everything feel okay again, no matter what my problem or worry. My purpose does not lie in my religion, it lies within my choices. And yes, I suppose if you are a "true" Christian, than God is ultimately your everything. But to me, that's only in Heaven. In life, you can't denounce the effect others have on you, just because Jesus holds a higher place with you. Think a little deeper, past God, and think about a personal situation. If someone pulled you from the brink, you would feel as though they could do anything, and that they were your everything. I can see how some parts can be interpreted as Christian, but overall I think it's a dedication to a loved one.