In Revelation God shows us an aspect of His Son, not shown to us in the gospels. In the Gospels we see Him as Savior, in Revelation as King; in John's Gospel as the Beginning, in Revelation as the Ending. The one displays love, the other His majesty.
In the upper room Jesus girds Himself about the waist for service; at Patmos He is discovered girt about the breast for war. In the Gospels His mild eyes melted Peter; in Revelation they are a flame of fire. There His voice was gentle, calling His own sheep by name, and gracious words proceeded out of His mouth; here His voice is terrible as the sound of many waters, and from His mouth there proceeds a sharp two-edged sword, striking death to His foes.
It is not enough that we know Jesus as the Lamb of God and as Savior of the world; we must know Him also as God's Christ, God's King, God's Judge. When we see Him as Savior, we say, "How lovable!" When we see Him as Monarch, we say, "How terrible!" and fall prostrate at His feet. The one issues in thanksgiving, the other worship. To see Him now as King is, one might almost say, to see "another" Christ.