John saw a new vision of the One he is to worship, the Lord Jesus Christ. Our passage describes John’s vision of the return of our Saviour as conquering King at the end of history. Heaven opens, and the Word of God—the incarnate Logos and Son of God (John 1:1–14)—appears on a white horse, leading the armies of heaven dressed in fine linen (Rev. 19:11–14)

Heidelberg Catechism Lord’s Day 19 Q/A 52