How do we know the white horse rider of Revelation 6 is the Antichrist and not Jesus?
Revelation 6's white horse rider lacks the descriptions that are equal to or attendant to Revelation 19, so he must be the counterfeit Christ, not Jesus. The counterfeit Christ is the Antichrist, the Son's counterpart in an unholy trinity that counterfeits the Father, Son, and Holy Spirit.
Les teaches that the key is comparison with Revelation 19. In Revelation 6, the rider on the white horse does not have the descriptions that are equal to or attendant to Revelation 19, so this rider has to be the counterfeit. The counterfeit Christ is the Antichrist. Les also places this within Revelation's unholy trinity: Satan counterfeits the Father, the Antichrist counterfeits the Son, and the false prophet counterfeits the Holy Spirit's work. He notes the false prophet is named as such in Revelation 19. Earlier, in Matthew, Jesus mentions angels attending His coming but does not mention saints in fine linen, white and clean; that secret was kept in the mind of God and not revealed until later. Because He is the perfect, sinless, errorless Son of God, He said only what was appropriate.