The word in Greek is "Abyss." Jerome's Vulgate left it untranslated. John Wycliffe rendered it "the pit of depnesse". But it's been William Tyndale's turn of phrase that has endured: "bottomless pit"! Rightly, the KJV decided it could not improve on Tyndale. The phrase occurs seven times, all in the book of Revelation (where sevens abound!). Take this representative example:
They had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon. (Revelation 9:11)
The sense of the "bottomless pit" (or "abyss") is an unbounded chaos. Infinite emptiness. An immeasurable depth. Limitless nothingness. This place of destruction and corruption is highlighted at the beginning and end of the Bible.
In the opening verses of Scripture we read about a void opened up in the creation of heaven and earth:
In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters. (Genesis 1:1-2)
"The deep" is the Abyss. And its presence is felt in the second verse of the Bible!
God, having created a reality beyond Himself, is faced, not with a mere extension of His divine being, but with something very distinct from Himself. God is light but here is darkness. God is full but here is an emptiness. In creation there is something beyond God which needs enlightening and filling full. This is what the work of creation involves. Over the six days God forms and then fills the universe, acting redemptively upon what is, by nature, "without form and void".
God separates light from darkness and sea from dry land. He divides and adjudicates - "Hitherto shalt thou come, but no further" (Job 38:11). God's creative work is all about undoing the abyss. He brings light, fullness and form - bounding the boundless.
Yet somehow there is a sphere that stands against the spreading goodness of God. There is an abyss. And it does not stand on an alternative foundation. The only true foundation can be the living God. Whatever stands against God cannot stand on anything substantial. No, God's enemies have nothing to stand on. Their realm is groundless - a bottomless pit.
Think about this negative reality. The realm of evil is not an equal and opposite kingdom. It is darkness, somehow resisting God's radiant light. It is a boundless emptiness, somehow resisting God's glory filling the earth. It is rebellion without a cause.
Sin and evil have no ultimate foundation, no reasons, no footing. They are madness. Those swallowed by the bottomless pit can only keep falling. Think of the tragedy: it's one kind of death to fall far - it's another to fall forever.
What hope is there in the face of this abyss?
Paul writes to the Romans to tell them that we have no hope against the powers of darkness. None of us can ascend to heaven and none of us can plumb the bottomless pit. But Christ has come down from the heights. And He has risen from the abyss:
Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above:) Or, Who shall descend into the deep [the abyss]? (that is, to bring up Christ again from the dead) (Romans 10:6-7)
We don't have to climb up to heaven and we don't have to climb out of the bottomless pit. Christ has done it all. He is the Radiant Light of the Father. He is the Spreading Goodness of God. And He has come to plunder Satan's house (Mark 3:27). He has entered into our darkness and risen to bring us home.
We cannot reason with evil - it's insanity. We cannot climb out of the bottomless pit - there is no footing. But Christ has done it all. We need only trust Him and He'll turn our pit to paradise:
If thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. (Romans 10:9)