C. S. Lewis on Love from Mere Christianity
"All sorts of people are fond of repeating the Christian statement that 'God is love'. But they seem not to notice that the words 'God is Love' have no real meaning unless God contains at least two Persons. Love is something one person has for another. If God was a single person, then before the world was made, He was not love. Of course, what these people mean when they say God is love is often something quite different: they really mean 'Love is God'. They really mean that our feelings of love, however and wherever they arise, and whatever results they produce, are to be treated with great respect. Perhaps they are: but that is something quite different from what Christians mean by the statement 'God is love'. They believe that the living, dynamic activity of love has been going on in God forever and has created anything else.
And that by the way, is perhaps the most important difference between Christianity and all other religions: that in Christianity God is not a static thing--not even a person--but a dynamic, pulsating activity, a life, almost a kind of drama. Almost, if you will not think me irreverent, a kind of dance. The union between the Father and the Son is such a live concrete thing that this union itself is also a person...of course, it is not a real person: it is only rather like a person. But that is just one of the differences between God and us. What grows out of the joint life of the Father and the Son is a real Person, is in fact the Third of the three Persons who are God. The third Person is called, in technical language, the Holy Ghost or the 'spirit' of God...
...And now, what does it all matter? It matters more than anything else in the world. The whole dance, or drama, or pattern of this three-Personal life is to be played out in each one of us: or (putting it the other way around) each one of us has to enter the pattern, take his place in that dance. There is no other way to the happiness for which we were made. Good things as well as bad, you know, are caught by a kind of infection. If you want to get warm you must stand near the fire: if you want to get wet you must get into the water. If you want joy, power, peace, eternal life, you must get close to, or even into, the thing that has them. They are not a sort of prize which God could, if He chose, just hand out to anyone. They are a great fountain of energy and beauty spurting up at the very centre of reality. If you are close to it, the spray will wet you: if you are not, you will remain dry. Once a man is united to God, how could he not live forever? Once a man is separated from God, what can he do but whither and die?"