who bare witness of the word of God, and of the testimony of Jesus Christ, even of all things that he saw.
John testifies here to the eternal Word of God, His only begotten Son, which is itself clear proof that the Apostle wrote this book. The Gospel he proclaims testifies of Christ's divinity and humanity, His offices as prophet, priest, and King, and all the grace His people receive through Him. His faithful witness to what he saw confirms the authority of this entire record.
AI summary
John testified the word of God in this book, what ancients would state in past tense where we say 'testifies.' The word of God constitutes his testimony; the oldest manuscripts omit the 'and,' so these phrases are in apposition: he witnessed all things that constitute the word of God and the testimony of Jesus, which is the Spirit of prophecy itself.
AI summary
Christ Himself is the great trustee of divine revelation, God gave it to Him as Mediator, He sent it by His angel, and through John it reaches the churches. Mark the beautiful order: God to Christ, Christ to the angel, the angel to the apostle, the apostle to us, so that we know what to expect from God and what He expects from us.
AI summary
Commenting on Revelation 1:1-2