Revelation 21:8

But for the fearful, and unbelieving, and abominable, and murderers, and fornicators, and sorcerers, and idolaters, and all liars, their part shall be in the lake that burneth with fire and brimstone; which is the second death.

The fearful ... Who are the fearful, if not all men? "But it is not of natural fear and timidity that John speaks; it is that cowardice which in the last resort chooses self and safety before Christ."[19] "It is not fear which is condemned. The highest courage is to be desperately afraid and in spite of that to do the right thing and to hold fast to loyalty."[20]

And unbelieving ... Unbelief is a gross, unpardonable sin, unless repented of. Unbelief is never a consequence of knowledge, education, intelligence, or "honesty." It is always a child of wickedness. See John 3:19, also article on "The Marvel of Unbelief," my Commentary on John, pp. 176-177, also in my Commentary on Matthew, pp. 207-209.

And abominable ... This is probably a reference, primarily, to participants in the rites of paganism and the unmentionable perversions and debaucheries that attended them. By extension, it also includes all sensualists of all ages.

Murderers ... fornicators ... sorcerers ... These sins have often been commented upon in this series; the principal significance of their appearance here lies in the fact that "God is the speaker!" These are not merely the preacher-prejudices of current religion, but the eternal laws of God against such things.

Idolaters ... and liars ... Idolatry, whether the worship of pagan gods, as in the days of John, or the worship and adoration of self above the God of heaven, can never be pleasing to God. No lie, however small, is a light thing in the eyes of God; and those whose lives are founded upon deceit and falsehood are indeed proscribed.

Fire and brimstone ... the second death ... This refers to the place of consignment for all those things for which God cannot allow any place in heaven.

[19] Leon Morris, Tyndale Bible Commentaries. New Testament, Vol. 20, Revelation (Grand Rapids, Michigan: Wm. B. Eerdmans Publishing Company, 1969), p. 246.

[20] William Barclay, The Revelation of John (Philadelphia: The Westminster Press, 1976), p. 206.