When a Pharisee asked Jesus what the greatest commandment in the law is, Jesus responded with the two greatest commandments: loving God and loving neighbor (see Mt 22:34-40). The two greatest commandments of God center on love (Greek: ἀγάπη). Naturally, readers of this passage might wonder, how do I love God and my neighbor?
Loving anything (or anyone) requires two steps: (1) choosing the object of one's love and (2) going out to the object loved and uniting with it. Additionally, Jesus emphasizes throughout the New Testament that love of God and those nearby involves sacrifice.
Jesus provided an example of sacrifice and calls his followers to do the same (i.e., to pick up their cross and follow him), but many people do not follow Christ's example or his call to sacrifice. Instead, they reduce sacrifice to warm feelings towards other human persons, and they reduce the act of love to giving from abundance. But giving only from abundance results in a simmering, tepid response to the need of another person. In contrast, sacrifice is the giving of oneself to another for the sake of the other's good. Warm feelings and simmering acts of love are not enough to be a real sacrifice.
A person who cannot sacrifice suffers from tepidity of soul. This tepidity negatively affects a person’s relationship with God, as Revelation 3:16 points out:
οὕτως ὅτι χλιαρὸς εἶ καὶ οὔτε ζεστὸς οὔτε ψυχρός. μέλλω σε ἐμέσαι ἐκ τοῦ στόματός μου (So because you are tepid, and neither fervent nor cold-hearted, I intend to vomit you out of my mouth.)
A tepid person neither lacks some good nor pursues some apparent good. A tepid person also does not knowingly commit evil acts. Rather, a tepid person says, "Πλούσιός εἰμι καὶ πεπλούτηκα καὶ ούδεν χρείαν ἔχω" (I am wealthy, and I have grown wealthy, and I have need of nothing). How can a person who thinks he or she has no need of anything sacrifice for anyone else? Such a person cannot see the needs of others and thus suffers from spiritual myopia. Consequently, any attempt to love made by this tepid person becomes distant and removed from real love.
In the Scripture passage quoted above, Jesus says he intends to vomit the tepid person from his mouth. The Greek word for vomit is ἐμέσαι and means to "utterly reject." Jesus intends to utterly reject the tepid person. Jesus works with the fervent and the cold-hearted because he can, but he cannot work with hearts that are in-between (i.e., tepid).
A tepid person thinks he or she has everything and has no need of Jesus. But does a tepid person really have everything? No. In Revelation 3:15-17, Jesus tells the tepid person that despite thinking he or she is wealthy, he or she is actually destitute. Jesus uses the Greek word πτωχός, which means absolute destitution, with no hope or way to remedy the destitute state. A person who is spiritually destitute does not have the means to remedy the situation on his or her own; this person can only find a remedy from Christ.
Although Jesus intends to completely reject a tepid person, Jesus, out of his infinite love, does not give up on that person. Jesus says,
ἰδοὺ ἕστηκα ἐπὶ τὴν θύραν καὶ κρούω ἐάν τις ἀκούσῃ τῆς φωνῆς μου καὶ ἀνοίξῃ τὴν θύραν εἰσελεύσομαι πρὸς αὐτὸν καὶδειπνήσω μετ΄ αὐτοῦ καὶ αὐτὸς μετ΄ ἐμοῦ (Behold, I stand at the door and knock. If anyone should hear my voice and open the door, then I will come in to him and will dine with him and he with me)
Jesus continuously knocks on the door of all hearts, waiting to dine with the soul. Dining in the ancient world was a very personal experience. Jesus wants to share his love with each person, in the very center of a soul. Jesus knocks and hopes that the tepid person will open the door. When a tepid person lets Jesus in, Jesus sets that person’s heart on fire with love.
This setting afire can be seen in William Holman Hunt’s painting of a passage from Revelation; this painting is called "Light of the World." In this painting, the door does not have a handle on the outside. Bishop Sheen spoke about how Hunt was excoriated by critics of his day for painting a door without a handle. These critics did not understand a fundamental truth about God and his relationship to our freedom: the door of the human heart only opens from the inside. Real love only occurs when both parties possess freedom to deny love of the other person. Nothing can replace the sublimity of a mutual "yes" to love.
No one is wealthy in love without Christ. Anyone who wants to truly love must open the door of his or her heart to Christ, who is love.