Revelation 6:1–8 introduces John’s vision of Jesus, the Lamb, opening the first four of seven seals. He also heard one of the four living creatures issue the thunderous command, ”Come!” What John saw next was the first calamity to strike the earth in the tribulation: seven years of judgment following the rapture of the church. There is no way to know whether the four horsemen follow each other sequentially or ride forth simultaneously. If they follow each other sequentially, we cannot know how much time elapses between their rides. The judgments appear to belong to the first half of the tribulation. However, some interpreters believe the sixth seal may be an exception.
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“Revelation 6:2” Bibleref.com
2 Then a white horse appeared, and he who sat on it had a bow. A crown was given to him, and he came out conquering, and to conquer.