In a letter attributed to St. John, one of the most direct statements about love is written in the Christian bible:

Beloved, let us love one another, because love is from God; everyone who loves is born of God and knows God. Whoever does not love does not know God, for God is love.  - 1 John 4:7-12

What is love? By John's account the answer to this question cannot be faced directly. In other words, we can't explain love adequately without accounting for the way it is given. "Love is from God." If any account of love is to begin therefore, it has to start with a denial of our ability define it in a reductively finite way. We mustn't reduce it to an account of human relationships, or marriage, or brotherly, sisterly or parental conditions. Notice that John does not say that love is God, but rathe that God is love. Love begins with God and it is God's love which is the condition for knowledge of God.

This is not to say that John is espousing an ethereal love that doesn't touch down in human life. God gives love.  Although our answer to the question what is love is indirect, John is ademant that an answer to this question is in fact given. As he goes on to say in his letter, "God's love was revealed among us in this way: God sent his only Son into the world so that we might live through him" (1John 4.9). If we're looking for love, John not only tells us that we must receive it as a gift, but that there are paradigmatic examples of that love embodied in the life and teaching of Jesus.

In this sense, John's account of love is utterly meaningless without Jesus. It is precisely insofar as Jesus is a human being that God's gift of love is truly real. The call to love in a Godly way is ultimately not an abandonment of our humanity, but its authentic fulfillment. As Martha Nussbaum puts it in her collection of essays, Love's Knowledge:

"Christianity seems to grant that in order to imagine a god who is truly superior, truly worthy of worship, truly and fully just, we must imagine a god who is human as well as divine, a god who has actually lived out the nontranscendent life and understands it in the only way it can be understood, by suffering and death." (p. 375)