You're actually the one trying to twist the Isaiah Scripture I quoted, even as you skipped to verse 15 instead of continuing at verse 12. I can do alot more than just quote it, for the Scripture is very EASY to understand.
You MIGHT want to go back to Isaiah 28 and pick up the main subject of who God is speaking those things to, and allow HIS Word to flow as written throughout, instead of trying to use it as prop for false witnessing against those who do accept God's Word as written about the literal existence of the abode for the wicked called hell.
Isa 30:8-33
8 Now go, write it before them in a table, and note it in a book, that it may be for the time to come for ever and ever:
9 That this is a rebellious people, lying children, children that will not hear the law of the LORD:
10 Which say to the seers, "See not; and to the prophets, Prophesy not unto us right things, speak unto us smooth things, prophesy deceits:
11 Get you out of the way, turn aside out of the path, cause the Holy One of Israel to cease from before us."
It's to the rebellious leaders of Jerusalem and of Ephraim, and those who listen to 'them' instead of God in His Word (Isaiah 28:1 and Isaiah 28:14). The Message was "for the time to come for ever and ever." So it still applies TODAY. The rebellious of His people don't want to hear God's called servants, the prophets of Isaiah's day, him being one of them. They even wanted God to cease from before them, so they could instead preach 'smooth things', 'deceits', instead of His Word as written. The preaching of no such thing as hell is the preaching of deceit. And God EMPHASIZED the existence of such a place in the Book of Isaiah, and at the END of this Isaiah 30 chapter.
12 Wherefore thus saith the Holy One of Israel, Because ye despise this word, and trust in oppression and perverseness, and stay thereon:
13 Therefore this iniquity shall be to you as a breach ready to fall, swelling out in a high wall, whose breaking cometh suddenly at an instant.
I wonder what time that event is for? Oh, it's for the end of this present world when God's Judgment will come upon the earth. The breaching of a false wall is an expression He used in several Scriptures, like Ezek.13, and Christ used it again about the foolish man that builds his house without a foundation. It's about the timeframe of Isaiah 29:5-6 when a destruction will come by God at an instant suddenly to end this world. It's about those of Isaiah 1:28. It's about the "sudden destruction" upon the deceived Apostle Paul foretold of in 1 Thess.5 on the day of The LORD when Christ's second coming will happen as a thief in the night. It's about the time Paul mentioned in 1 Cor.15 will come "at the twinkling of an eye". It's the time Peter declared in 2 Pet.3 when man's works on this earth will burn with fervent heat by God's consuming fire. That's when 'their' false foundation wall tempered with mortar will come down. As written in Isaiah, God's Hand is stretched out still, ready to strike on that day.
14 And He shall break it as the breaking of the potters' vessel that is broken in pieces; He shall not spare: so that there shall not be found in the bursting of it a sherd to take fire from the hearth, or to take water withal out of the pit.
Their false wall is going to be broken into tiny pieces like a potter's vessel; not even a shard (sherd) big enough to draw water will be left on that day. HARD WORDS they ARE, but not from me, but from my Heavenly Father. He said it, and He will do it. Count on it.
15 For thus saith the Lord GOD, the Holy One of Israel; In returning and rest shall ye be saved; in quietness and in confidence shall be your strength: and ye would not.
By returning to GOD and His Way and in His Rest one is saved, which brings quietness to the soul and confidence and strength from God. But they wouldn't have it. They instead want to muzzle Him and create their own 'way', which is a false wall of confusion, ready to fall as soon as a strong wind hits it.
16 But ye said, "No; for we will flee upon horses"; therefore shall ye flee: and, "We will ride upon the swift"; therefore shall they that pursue you be swift.
Got to read it with proper quotation. Those who refuse God's Way when asked to return to Him instead say, "No, for we will flee upon horses". God then replies, "therefore shall ye flee", and it's in the sense of fleeing for fear. And they say, "We will ride upon the swift", and God replies, "therefore shall they that pursue you be swift", meaning those who turn from His Word can TRY to flee, but they will be pursued just as quickly.
17 One thousand shall flee at the rebuke of one; at the rebuke of five shall ye flee: till ye be left as a beacon upon the top of a mountain, and as an ensign on an hill.
The coming rebuke upon those false leaders of His people, and those who follow them, will leave them as a tree upon a hilll stripped naked of all its outer bark, serving as a warning sign (beacon) for others to not go that way (see Hebrew of that verse).
18 And therefore will the LORD wait, that He may be gracious unto you, and therefore will He be exalted, that He may have mercy upon you: for the LORD is a God of judgment: blessed are all they that wait for Him.
GOD gave a CONDITION for one to be among these that He will be gracious to. It's ONLY about those who WAIT for Him. That's what the events of the last days is going to boil down to, those who wait for His return regardless of the amount of persecution they will have to endure, and then there are those that will not wait, but will bow to worship a false one instead. The false leaders and followers of His people are those who will not wait, but intend to setup their 'own' messiah in place of Christ Jesus just prior to His return. There is no room for a 'hell' in their false religion. Christ Jesus warned about a fake Christ who comes first, and His Apostles did also.
19 For the people shall dwell in Zion at Jerusalem: thou shalt weep no more: He will be very gracious unto thee at the voice of thy cry; when He shall hear it, He will answer thee.
Will those who turn away from Him, that say preach deceits be among those? NO! Isaiah 24:22 already told us what is going to happen to those when Christ returns...
Isa 24:21-22
21 And it shall come to pass in that day, that the LORD shall punish the host of the high ones that are on high, and the kings of the earth upon the earth.
22 And they shall be gathered together, as prisoners are gathered in the pit, and shall be shut up in the prison, and after many days shall they be visited.
(KJV)
Isaiah 30:20 And though the Lord give you the bread of adversity, and the water of affliction, yet shall not thy teachers be removed into a corner any more, but thine eyes shall see thy teachers:
21 And thine ears shall hear a word behind thee, saying, "This is the way, walk ye in it, when ye turn to the right hand, and when ye turn to the left."
22 Ye shall defile also the covering of thy graven images of silver, and the ornament of thy molten images of gold: thou shalt cast them away as a menstruous cloth; thou shalt say unto it, "Get thee hence."
God's true called and chosen teachers will not be cast into a corner anymore in that day. God is going to remove the blindness of the faithful of His people in that future time. They will throw away their idols like a dirty menstruous cloth when their blindness is removed. But those wicked leaders of His people? They'll be in the pit of hell like Isaiah 24 says, the very prison pit where Satan will be locked during Christ's thousand years reign on earth with His elect (Rev.20).
23 Then shall He give the rain of thy seed, that thou shalt sow the ground withal; and bread of the increase of the earth, and it shall be fat and plenteous: in that day shall thy cattle feed in large pastures.
24 The oxen likewise and the young asses that ear the ground shall eat clean provender, which hath been winnowed with the shovel and with the fan.
25 And there shall be upon every high mountain, and upon every high hill, rivers and streams of waters in the day of the great slaughter, when the towers fall.
26 Moreover the light of the moon shall be as the light of the sun, and the light of the sun shall be sevenfold, as the light of seven days, in the day that the LORD bindeth up the breach of His people, and healeth the stroke of their wound.
That is all about the future Milennium reign of Christ Jesus and His elect upon Mount Zion in the new Jerusalem, on earth. Houses will be built, vineyards planted, and the people will enjoy the fruits of their labors, and no man will take it away. Will the rebellious take part in that? No.
27 Behold, the name of the LORD cometh from far, burning with His anger, and the burden thereof is heavy: His lips are full of indignation, and His tongue as a devouring fire:
28 And His breath, as an overflowing stream, shall reach to the midst of the neck, to sift the nations with the sieve of vanity: and there shall be a bridle in the jaws of the people, causing them to err.
Now the subject is back to the future time of judgment at Christ's return and God's consuming fire to end this present world. That's when that sifting of the nations is going to happen, the angels separating His sheep on the right from the "goats" on the left (Matt.25).
29 Ye shall have a song, as in the night when a holy solemnity is kept; and gladness of heart, as when one goeth with a pipe to come into the mountain of the LORD, to the mighty One of Israel.
30 And the LORD shall cause His glorious voice to be heard, and shall shew the lighting down of His arm, with the indignation of His anger, and with the flame of a devouring fire, with scattering, and tempest, and hailstones.
Who will be singing the song of Moses upon Mount Zion in Christ's Presence? The rebellious? No. It will only be those who WAIT for His return to do a sudden destruction upon the wicked at an instant suddenly on the day of The LORD. Those hailstones upon Satan's army at Armageddon will weigh a talent (per Rev.16).
31 For through the voice of the LORD shall the Assyrian be beaten down, which smote with a rod.
32 And in every place where the grounded staff shall pass, which the LORD shall lay upon him, it shall be with tabrets and harps: and in battles of shaking will He fight with it.
As written at the end of Hebrews 12, God is going to shake this earth yet once more to remove what the wicked have created, so that only those things He created will remain. The Assyrian here is being used as a symbolic title for Satan.
33 For Tophet is ordained of old; yea, for the king it is prepared; He hath made it deep and large: the pile thereof is fire and much wood; the breath of the LORD, like a stream of brimstone, doth kindle it.
(KJV)
Tophet was about the perpetual burning garbage pit outside Jerusalem's walls where Israel fell away to infant sacrifices. God compares that place with the "lake of fire" of Rev.20:14 that the abode of hell, death, Satan and the wicked, will perish in. Christ used it also when speaking of "hell" (geena).
