God sent the Muslims to kill the Trinitarians

The trumpet sounding of the fifth angel is followed by a star falling from heaven unto the earth with a key to open the bottomless pit. On the opening of the pit, the sun and air is darkened by the ascending smoke, out of which pour a cloud of locusts. They are commanded to avoid any green foliage, and attack only those men who have not the seal of God in their foreheads. This they do for some months, moving as cavalry under the direction of a king. The sounding of the sixth angel is followed by the releasing of four angels bound in the great river Euphrates. They lead a vast horde of cavalrymen to battle, as a result of which, the third of men are killed. The Eastern Empire is thus brought to an end, but even this tragedy does not cause the rest of mankind to cease from their sin and blasphemy against Almighty God

The "star" was Mahomet. It is appropriate to the symbol, that Arabia, the region from whence Mahomet originated, is noted for the remarkable depression of the Arabah, the Jordan Valley and the area around the Dead Sea. This is the lowest point of the earth's surface which is above water, so that the term "abyss" is appropriate to it. Mahomet was born about the year 570, and belonged to the Koreish clan, whose special privilege and duty it was to guard the sacred Black Stone at Mecca.
Mahomet was still a young man when he commenced his "great imposture," declaring that he was a "prophet" in communion with God, and had been appointed to set before the people the true religion. The people of Mecca, who made no small gain out of the Black Stone, drove Mahomet from the city, and he fled to Medina. Mahomet wrote the Koran, and proclaimed the tenets of Mahommedanism. Gradually the number of his converts increased. Proclaiming his belief in one God, he declared open war upon the Trinitarians of the Greek and Roman Catholics. As his power grew, he sent ambassadors to the court of Constantinople, and when they were contemptuously rejected by the authorities of the eastern Roman Empire, he decided to overthrow it by force. The way, or shaft to the abyss was domination of the Middle East. Accordingly he laid claim to Arabia, and then made preparations for an attack on the bastionof the eastern Empire. He died in 632 before he could accomplish this, and was succeeded by Abubeker, the first Caliph.