Rev 6:4

“For, in coming to the High Priest of the Father-Christ-all impediments must first be taken away, in the space of a week, that the house which remains, the flesh and the soul, may be clean; and when the Word of God has entered it, and has found "stains of red and green," forthwith must the deadly and sanguinary passions "be extracted" and "cast away" out of doors-for the Apocalypse withal has set "death" upon a "green horse," but a "warrior" upon a "red" -and in their stead must be under-strewn stones polished and apt for conjunction, and firm,-such as are made (by God) into (sons) of Abraham, -that thus the man may be fit for God.”

“The red horse comes out against the victorious and conquering church. That is, there comes an evil and wicked people, made bloody from its rider, the devil. This is just as we read in Zechariah concerning the red horse of the Lord, except that there it is red from his own blood, while here it is red from the blood of others. "And to him a great sword was given, to take peace from the earth." This refers to the peace of the earth, for the church possesses an eternal peace that Christ left behind for himself. As we noted above, the white horse is the church and its rider is Christ or the Holy Spirit in whose hand is a bow that sends forth his commandments, as though they were powerful, sharp arrows, throughout the whole world both to kill sins and to enliven the hearts of the faithful. The crown upon his head is the promise of eternal life. Here, … the red horse is an evil people whose rider is the devil. It is said to be red because it has been made red with the blood of multitudes. And a sharp sword was given to it to take peace from the earth. This means that with the devil's connivance and influence evil people join together and do not cease to incite among themselves strife and dissension, even unto death.”

“We suggest that this second seal is to be interpreted as the succession of the apostles that is fulfilled through martyrs and teachers. During this succession, as the proclamation is extended abroad, the peace of the world is taken away, creation being divided against itself, as was spoken by the Lord: "I have not come to bring peace on earth, but a sword." And by this [sword] the sacrifices of the martyrs are offered on the heavenly altar. The "red horse" is symbolic either of the shedding of blood or of the red-hot disposition of those who suffer for Christ. The words "it was permitted to its rider to take peace" show the all-wise permission of God that tests his faithful servants through temptations.”

“And a great sword was given to him. Either against those who become apostates of the faith, or against those whom he makes martyrs. About this, it is said to blessed Job: He who made him applied his sword (Job 40), meaning either that he should not tempt the saints as much as the wicked one wishes, or that vengeance for his fury should return upon himself.”

“And there went out another horse that was red: and to him that sat thereon, it was given that he should take peace from the earth. The red horse is the body of the old enemy, that is all the reprobates, blood-red due to their killing of souls. While the rider of the elect says, My peace I give unto you, [John 14:27] the rider of the reprobates takes peace from the earth, because the former is the author of concord, while the latter is the author of discord. Note also that he takes peace not from heaven, but from the earth, that is from those who seek earthly things. And that they should kill one another. It is not a fleshly but a spiritual killing that should be understood in this sentence. As for how the reprobates are to kill one another, it is disclosed when it is said after that about the prince of the Jews, and a great sword was given to him, that is a spiritual and evil sword with which not the bodies, but the souls of the reprobates are killed. The Devil uses this sword in two ways: he either deceives people by himself on the inside with a spiritual speech or achieves the killing of the soul by assailing them from the outside through the tongues of his fleshly servants. All this is said to have been given him, which means that it was permitted him by the just God who disposes everything.”