One of the marks of the remnant in Rev. 12:17 is that they are those who “have” or “hold to” (Greek: echontôn) the “testimony of Jesus” (Greek: tên marturion Iêsou). Many scholars see this phrase as representing either the gospel (Jesus’ testimony about the character of God in His life—John 14:9) or the book of Revelation itself (Rev. 1:1-3). But a closer look at Revelation 1:1-3 indicates that the “testimony of Jesus” is neither of these in Revelation.
Revelation 1:1-3 portrays a chain of revelation. The revelation is passed from God to Jesus, then from Jesus through His angel to His servant John and then John writes it out for the people. What God gives to Jesus is called “the revelation of Jesus Christ.” What Jesus gives to John is called “the testimony of Jesus.” What John gives to the people is called “the words of this prophecy.” Summarizing this chain of revelation in different words, based on the text: The revelation of Jesus Christ is what God gave. The testimony of Jesus is what John saw. The words of this prophecy are what John wrote. That means that the testimony of Jesus is not the book of Revelation (what John wrote), it is the visionary gift that Jesus gave to John (what John saw—Rev. 1:2). So the testimony of Jesus is a visionary gift of revelation that he gave to John according to the second verse of the book.
One of the marks of the remnant is having the “testimony of Jesus” (Rev. 12:17—Greek: echontôn tên marturian iêsou). Based on the evidence of Revelation 1:1-3, this means that John foresaw an end-time revival of the kind of visionary, prophetic gift he was given (Rev. 1:2). This reading of 12:17 is confirmed when you compare Revelation 12:17 with a careful comparison of Rev 19:10 and 22:8-9. Revelation 19:10 speaks of John’s “brothers. . . who have the testimony of Jesus” (Greek: tôn echontôn tên marturian iêsou). The two phrases are identical. The further parallel with Revelation 22:9 is instructive. In a very similar scene the angel speaks of John’s brothers “the prophets.” So the testimony of Jesus is closely associated with the gift of prophecy in Revelation. Those who “have the testimony of Jesus” in 19:10 are called “the prophets” in 22:9. This confirms that the mark of the remnant in Revelation 12:17 described as “the testimony of Jesus” represents the kind of visionary, prophetic gift that John himself had.