25 See that you do not refuse Him who speaks. For if they did not escape who refused Him who spoke on earth, much more shall we not escape if we turn away from Him who speaks from heaven,
26 whose voice then shook the earth; but now He has promised, saying, “Yet once more I shake not only the earth, but also heaven.”
27 Now this, “Yet once more,” indicates the removal of those things that are being shaken, as of things that are made, that the things which cannot be shaken may remain.
28 Therefore, since we are receiving a kingdom which cannot be shaken, let us have grace, by which we may serve God acceptably with reverence and godly fear.
29 For our God is a consuming fire.
Those who rejected God’s message from Mt. Sinai through angels, didn’t escape judgment. Those who reject God’s message in Christ (Hebrews 1:2) won’t either.
see (v.25) = see to it — continuous action
they (v.25) — Israel in the Exodus
if we turn away (v.25) — action then going on
shook the earth (v.26) — Exodus 19:18 — Haggai 2:6 — judgment at Christ’s second coming (2 Peter 3:10, 12; Revelation 20:11; 21:1-5; Isaiah 65:17; 66:22)
The writer quotes the prophecy of Haggai 2:6. This will be fulfilled during the Great Tribulation perod at which time the movements and functions of the heavenly bodies will be disorganized (Revelation 6:12-17), 8:12), and an earthquake will shake the entire earth, occurring at the moment the Messiah’s feet touch the Mount of Olives at he close of the Great Tribulation (Zechariah 14:4-5; Revelation 6:12; 11:13; 16:18) — Hebrews in the Greek New Testament, by Kenneth S. Wuest, page 230.
things that are made (v.27) — temporary things — The destruction of temporary things highlights permanent things
have grace (v.28) — be grateful
reverence (v.28) = caution, discretion
godly fear (v.28) = apprehension of danger (not terror) — regard for God and His standards
Verse 29 is a quote from Deuteronomy 4:24