In John’s amazing vision as recorded in the first three chapters of Revelation, he sees Jesus walking in the midst of the seven New Testament churches of Asia. Christ's eyes are aflame, and He is wearing priestly clothes. It is clear that He has come to judge these churches in righteousness.
Peter writes, "Judgment must begin at the house of God" (1 Peter 4:17). And now, as Jesus appears among the seven churches, He begins to judge them according to both the good and bad He beholds. These judgments appear in Revelation 2 and 3, both red letter chapters, meaning every word comes directly from Jesus' lips.
Now, these seven churches were actual congregations in real localities: Ephesus, Smyrna, Laodicea, and so on. Yet John hears God's voice speaking not only to these particular churches, but to the church universal — indeed, to every believer who looks for Jesus' soon return.
Jesus begins His judgments by listing the many good things about the churches that bless Him, and He compliments each church on these things. But He also sees several things that grieve Him deeply and He issues a warning to each church.
His first message is to the Christians at Ephesus, a church founded on the godly teaching of the apostle Paul. Jesus' judgment of the Ephesians is, "Thou hast left thy first love" (Revelation 2:4).
When Jesus uses the words first love here, He is not speaking of the immature love we experience when we are first saved. Rather, He is talking about exclusive love: "I once occupied first place in your heart but now you have lost the exclusivity of your love for Me. You have allowed other things to take My place."
It is significant that of all the sins Jesus points out in these seven churches — adultery, covetousness, lukewarmness, false teachings, Jezebels in authority, dead worship, spiritual blindness — the first sin He names is the one that grieves Him most: a loss of affection for Him. Our God is a jealous lover and He will not allow anything to come before our love for Him.