(Revelation 1:1-2) The Revelation of Jesus Christ, which God gave Him to show His servants things which must shortly take place. And He sent and signified it by His angel to His servant John, who bore witness to the word of God, and to the testimony of Jesus Christ, to all things that he saw.
The spiritual Author of the book of Revelation is God, but the human author was the apostle John. This is the John of the Gospels, one of the twelve disciples of Jesus. Within the pages of Revelation, John identifies himself five times as the one who experienced these heaven-sent visions. (Rev. 1:1, 4, 9; 21:2; 22:8).
John specifies that he literally wrote down what “he saw” in vision, only the facts, unadulterated truth. Just as he was an eyewitness to the earthly life of Jesus, so he was to Christ’s prophetic revelation. Here, we also have the book’s first reference “to the testimony of Jesus Christ” This phrase also appears in Revelation 1:9 and 12:17; then in 19:10, we learn that “the testimony of Jesus is the spirit of prophecy”
So John was simply writing down a prophetic message from the Holy Spirit, who is described as the quintessential witness of the truth (John 15:26; 16:13; 1 John 5:6). Since we already know what “signified” means, the question still remains: Why was the letter “signified” through a kaleidoscope of sometimes bizarre symbols and signs? John was the only living disciple who had walked with Jesus because all the rest, excepting Judas, had been martyred for their faith. Think how vital it was for this most important message for God’s people to be hidden from ruthless adversaries who would destroy it, yet still be able to be unveiled to the careful student of Scripture, humbly searching for truth. These symbols and beasts are no longer a mystery and expose some pretty serious institutions and governments. Were they written directly they would have been destroyed. Instead they have been preserved through the ages to our day today as a warning to us for what is to come.