The trouble is, I don't think we all mean the same thing when we use the term. Lay theologian C.S. Lewis (and the Greeks before him) once identified four different uses of the term love: affection (i.e., fondness), friendship (i.e., strong bond), eros (i.e., being in love), and charity (i.e., the love that calls on us to care for others regardless of the circumstances). To this list, I would be tempted to add a couple more. For example, my sense is that when a lot of people hear the word, they think of Dr. Phil, Oprah, Psychology Today and "warm fuzzes." However, while I'm certain that Jesus offered comfort to the afflicted, if Jesus had only made people feel good, he never would have been nailed to a cross by the Romans for sedition. Then, of course, some of us see God's love in terms of parental love, but even here, how we view God is split between those of us who see him as a firm parent and those of us who see him (or her) as an indulgent one. As Froese and Bader note,
Some parents stress self-discipline, responsibility, and self-reliance in order to help their children become independent and happy individuals... They believe that the goodness of a child is enhanced by tenaciously reprimanding any behavior that strays from the right path. Other parents stress fairness and equality and seek to guide children without reprimands but rather through enticements. For these parents, punishment instills the wrong message and, in fact, tends to squelch the freedom and independence of a child (p. 16).To illustrate this latter divide, consider the debate over the place of gay and lesbians in the Church. Both conservative and liberal Christians agree that the Church should love gays and lesbians. However, while for the former this generally means tough love, for the latter it tends to mean being nonjudgmental. That is, theological conservatives are more likely to believe that the proper response of the Church is to love the sinner but not the sin and promote the Gospel's power to help gays and lesbians to either transcend or transform their sexual desires (i.e., either not act on their impulses or become straight). By contrast, theological liberals are more likely to accept gays and lesbians as they are (i.e., not requiring them to repent of their sinfulness because they don't consider them to be sinful), and to welcome them as full and faithful members of the Church.
Jesus and Love in the Gospels
This emphasis on the centrality of love among mainline Christians is puzzling since it is likely that Jesus hardly ever used the term. The word love seldom appears on Jesus' lips except in the Gospel of John, which (unless one takes a noncritical approach to the Bible) tells us little about the historical Jesus. As New Testament scholar John Meier notes in the fourth volume of his examination of the historical Jesus,
Most believers take for granted that what lies at the heart of Jesus' message and what is repeated incessantly throughout his preaching is love, both love of neighbor and love of enemies. This is the received "gospel" generations who have grown up believing that all you need is love. However, if we restrict ourselves for the moment to the Synoptic Gospels, one would not get such an impression from the saying of Jesus. "Love" as a verb or noun occurs relatively rarely on the lips of Jesus. When it does occur, Jesus is often citing a text from the Jewish Scriptures or commenting on it (A Marginal Jew: Law and Love, pp. 480-481).In fact, Meier only traces two sayings back to the historical Jesus: (1) the double command to love God and one's neighbors and (2) the command to love one's enemies. He concludes his analysis by claiming that we cannot understand Jesus' use of the word love apart from his understanding of Torah, and that we shouldn't place "love" at the center of Jesus' theology:
Once we move on to claiming that Jesus made love the hermeneutical key for interpreting the whole Law or the supreme principle from which all other commandments can be deduced or by which they can be judged, we have shifted from the historical Jesus to the Matthean Jesus--the original sin of most Christian exegetes expounding on the historical Jesus and the Law... All you need is love? Hardly. For Jesus, you need the Torah as a whole. Nothing could be more foreign to this Palestinian Jew than a facile antithesis between Law and love. But love, as commanded by the Law, comes first--and second" (p. 576).Love and Christian Theology
What then does this imply for contemporary theological reflection and proclamation? Well, it certainly doesn't mean that Christians have to abandon notions of love. However, when we do use it (unless we are going to assume that our congregants are familiar with both the Oral and Written Torah), we need to embed it within the story of Jesus' life, death, teachings and Resurrection. We need to place it within a distinctly Christian context because what love meant for Jesus and what it means for Christians differs from what it means in more secular settings. That doesn't mean there isn't some overlap between these different "worlds," but they aren't identical, and given the variety of ways in which the word is used and interpreted, Christians need to be careful how they use it.
That said, we also need to avoid the temptation of treating love as the central Christian theological concept. As we've already seen, to do so isn't supported by the textual evidence. Moreover, there are other concepts that are central to the Christian faith (e.g., hope, forgiveness, redemption, sin) that stand on their own, so to speak, and should not be seen as being derived from love.
Thus, with all due respect to John Lennon, while it is true that we do need love, love is not all we need.