John has experienced that the good progress of the gospel received pushback from many hearers as they rejected the message of redemption (see 1 John 2:19). In fact, he was himself a prisoner on account of the gospel (Revelation 1:9), and the letters of Jesus Christ to the seven churches indicate that the churches experienced (and would experience) resistance to the gospel. The Lord God, however, would not permit resistance to triumph on earth; on resistance and rejection must come plagues from the Lord of lords (see Genesis 2:17 as worked out in Leviticus 26:1–46; Deuteronomy 28:1–68). This is the connection between the first horse and the three that follow. The plagues represented by those three horses receive their climax in the judgment of the Last Day as described in opening of the sixth seal.
The first horse has gone out conquering and to conquer,
which describes what the gospel does ceaselessly in the course of New Testament history. The other three horses are ready to go whenever the Lord is pleased to send his plagues upon the earth. From time to time he sends those horses with their plagues in response to rejection of the gospel. The Lord does not destroy his enemies yet; he is patient as he presses his hand of judgment upon the stubborn, not wanting any to perish but giving space for repentance (see Romans 2:4; 2 Peter 3:9).
1 Now I watched when the Lamb opened one of the seven seals, and I heard one of the four living creatures say with a voice like thunder, “Come!”