4. certain men--implying disparagement.
      crept in unawares--stealthily and unlawfully. See on 2Pe 2:1, "privily shall bring in damnable heresies."
      before . . . ordained--Greek, "forewritten," namely, in Peter's prophecy Jude 17, 18; and in Paul's before that, 1Ti 4:1; 2Ti 3:1; and by implication in the judgments which overtook the apostate angels. The disobedient Israelites, Sodom and Gomorrah, Balaam and Core, and which are written "for an example" (Jude 7, and Jude 5, 6, 11). God's eternal character as the Punisher of sin, as set forth in Scripture "of old," is the ground on which such apostate characters are ordained to condemnation. Scripture is the reflection of God's book of life in which believers are "written among the living." "Forewritten" is applied also in Ro 15:4 to the things written in Scripture. Scripture itself reflects God's character from everlasting, which is the ground of His decrees from everlasting. BENGEL explains it as an abbreviated phrase for, "They were of old foretold by Enoch (Jude 14, who did not write his prophecies), and afterwards marked out by the written word."
      to this condemnation--Jude graphically puts their judgment as it were present before the eyes, "THIS." Enoch's prophecy comprises the "ungodly men" of the last days before Christ's coming to judgment, as well as their forerunners, the "ungodly men" before the flood, the type of the last judgment (Mt 24:37-39; 2Pe 3:3-7). The disposition and the doom of both correspond.
      the grace of our God--A phrase for the Gospel especially sweet to believers who appropriate God in Christ as "our God," and so rendering the more odious the vile perversity of those who turn the Gospel state of grace and liberty into a ground of licentiousness, as if their exemption from the law gave them a license to sin.
      denying the only Lord--The oldest manuscripts, versions, and Fathers omit "God," which follows in English Version. Translate as the Greek, "the only Master"; here used of Jesus Christ, who is at once Master and "Lord" (a different Greek word). See on 2Pe 2:1. By virtue of Christ's perfect oneness with the Father, He, as well as the Father, is termed "the ONLY" God and "MASTER." Greek, "Master," implies God's absolute ownership to dispose of His creatures as He likes.

JFB.