1. God’s love is incomprehensible.
No human mind can comprehend God. We cannot define God. We cannot provide a comprehensive account of who he is. He “dwells in unapproachable light” (1 Tim. 6:16). If God is incomprehensible, then so is his love. While we may and must speak truthfully about his love, we can never fathom it, because it is divine love, as different from our love as his being is different from our being.
2. God’s love can be known.
We cannot define God in the sense of delimiting exhaustively who he is, but we can nonetheless describe him truthfully. We can do so because he has made himself known to us in his Word and he opens our eyes to that Word by his Spirit. How is that possible, given the divine difference? It is possible because God makes himself known to us in creaturely reality. He takes up the things he has made and uses them to describe himself to us. Thus he is a lion, a rock, fire, even moth and dry rot (look it up!).
3. God is known by analogy.
When God uses created things like lions to speak about himself in the Bible he is speaking analogically. This means that the things he uses to describe himself are neither identical with him, nor utterly different from him. He is a rock, for example, not because he is made of stone. When he says “rock” of himself, we are not to map all the rockiness of a rock onto him point-for-point. But nor are we to think that he is he entirely unrocky, discontinuous in every way with rocks. When he says that he is a rock he means some of what we mean when we say that a rock is a rock: he is not made of stone, but he is solid and reliable. How is it possible for created things to image God for us like this? It is possible precisely because he created them. It is as if his fingerprints are left on the things he has made, so that each of them contains a pale reflection of some of his divine attributes. Our fallen minds cannot piece together a picture of God from what he has made—indeed we suppress his natural revelation — but in his inspired Word he himself can use those things to describe himself, and then he can illuminate our minds to understand and believe those descriptions. This all applies to God’s love: when we read “God is love” we know something of what love is from what he has made, but his love is never to be identified point-for-point with any created love that we already know.