So shall they fear the name of the LORD from the west, and his glory
from the rising of the sun. When the enemy shall come in like a flood,
the Spirit of the LORD shall lift up a standard against him(Isa. 59:19).
The Context for undertanding this passage is Figurative, as the "Woman" and "Dragon" are representitive of another reality, and not 'Literally' "a woman", or "a dragon".
The "Dragon", from the previous verses (vs. 3) is,
And there appeared another wonderb in heaven; and behold a great red
dragon, having seven heads and ten horns, and seven crowns upon his
heads.
The "7 Head and 10 Horns" are kingdoms; we see Rev. 17:10 are kingdoms,"
And there are seven kings: five are fallen, and one is, and the other
is not yet come; and when he cometh, he must continue a short space.
We see also that the "horns" are kingdoms also,"
And the ten horns which thou sawest are ten kings, which have received
no kingdom as yet; but receive power as kings one hour with the beast(vs 12)
Crucial to understanding this question is understanding the "Crowns"; from Rev. 17:12 we see that "power is given to them for 1 hour"-obviously not "60 Minutes" but a shorter period of time, so the Crowns indicate WHO is reigning at the point of time the vision is seen. In Rev. 12 the "Head" kingdoms are reigning; in Rev. 13, the "Horn" kingdoms are reigning.
"And his tail drew the third part of the stars of heaven, and did cast
them to the earth: and the dragon stood before the woman which was
ready to be delivered , for to devour her child as soon as it was born
. 5And she brought forth a man child, who was to rule all nations with
a rod of iron: and her child was caught up unto God, and to his throne".(Rev. 12:4-5)
The man-child who "rules all the nations with a rod of iron" is Christ; Ps. 2:6-9 says,"
Yet have I set my king upon my holy hill of Zion. 7 I will declare
the decree: the Lord hath said unto me, Thou art my Son; this day have
I begotten thee. 8 Ask of me, and I shall give thee the heathen for
thine inheritance, and the uttermost parts of the earth for thy
possession. 9 Thou shalt break them with a rod of iron; thou shalt
dash them in pieces like a potter's vessel.
The "woman" must be understood in Figurative context, since the rest of the chapter is understood figuratively. Mary, of course, was Jesus's earthly mother, and Christ's appearance on earth was during the Roman Empire, this is described to John as a "Head that is"(Rev. 17:10," And there are seven kings: five are fallen, and one is." Satan can be seen as 'empowering' the dragon; 'red' is the color of blood. In the following verses, Satan and his angels are removed from Heaven,"
And the dragon was wroth with the woman, and went to make war with the
remnant of her seed, which keep the commandments of God, and have the
testimony of Jesus Christ.(vs 17)
From this verse we see the "Woman" is more than Mary, although she is a type; "her seed" are all the believers of Jesus as the Son of God, she is "Spiritual Israel", or the 'mother' of all those who believe the promises of God,"
And I will put enmity between thee and the woman, and between thy seed
and her seed; it shall bruise thy head, and thou shalt bruise his
heel.(Gen. 3:15)
It is this backround which we must lay 1st before addressing the question: "What does the earth opening it's mouth mean?"
Twice in this chapter God protects the woman by bringing her to the wilderness; the 1st time, in vs 6 she is there for 1260 days. This can be the time Mary and Joseph, who being warned by an angel, fled to Egypt(Matt. 2:14) although historians differ about the length of time, judging from the death of Herod. The distinction must be made from the "1260 days" which at least approximates the time in Egypt, to the 'time, times and a half', which describe a period of time, but not the same time as "1260 days".
The 1260 days also roughly approximate the time of Jesus's earthly ministry; since we have ascertained that the 'woman' was Spiritual Israel, she was protected, so that "none were lost, except the son of perdition"(John 17:12); each time there was a threat, Jesus 'withdrew to the wilderness',
"Jesus therefore walked no more openly among the Jews; but
went thence unto a country near to the wilderness, into a city called
Ephraim, and there continued with his disciples."(John 11:54)
The "wilderness" was the place where God sent His prophets to encounter Him(think Elijah, Moses, John the Baptist, etc.) and also the place we encounter God. Since the "woman was given "2 wings of an eagle"(vs 14), symbolic of God's Sovereign protection,
"Ye have seen what I did unto the Egyptians, and how I bare you on
eagles' wings, and brought you unto myself.(Ex. 19:4)
God had given the 'woman' the ability to survive the onslaught of persecution from the "Roman Empire/Antichrist nations/Beast" which came during the 1st 3 centuries of Christianity largely by preserving it's doctrinal integrity in the 'wilderness'; the Desert Fathers in Egypt, John on Patmos, the various places that Christianity(Asia Minor, Macedonia, France, Brittain, etc.) all because of the persecution that had sent the Church out of Jerusalem to the ends of the earth. Just as the "earth opened it's mouth" and prevented Herod from pursuing Joseph and Mary, so also did the earth "open it's mouth" and prevent Christianity from being destroyed at any major population center, causing instead Christianity to "flee to the wilderness" to be re-invigorated with a fresh perspective from God.