The Two Mountains (3): Mount Sion and Mount Sinai: The Exhortation (Hebrews 12:25-29) by Rev. Angus Stewart
I. The Warning of No Escape
II. The Shaking of Heaven and Earth
III. The Calling to Godly Fear
John Owen on Hebrews 12:26-27: "This is the conclusion of the whole argumentative part of this epistle, that which was aimed at from the beginning. Having fully proved the excellency of the gospel, and state of the church therein, above that under the law, and confirmed it by an examination of all the concernments of the one and the other, as we have seen; he now declares from the Scripture, according to his usual way of dealing with those Hebrews, that all the ancient institutions of worship, and the whole church-state of the old covenant, were now to be removed and taken away; and that to make way for a better state, more glorious, and that which should never be obnoxious to change or alteration" (Hebrews, vol. 7, pp 366-367)
For more, see Eschatology Resources: http://www.cprf.co.uk/eschatologyresources.htm