Summary: The ungodly have crept into the church (Jude 4). Jesus is coming and they will be judged. All the ungodly will be judged. What side of Judgment are you on?
In 1935, an umpire in his rookie year, named Ralp “Babe” Pinelli once called Babe Ruth out on strikes. When the crowd booed with sharp disapproval at the call, the legendary Ruth turned to the umpire with disdain and said, "There’s 40,000 people here who know that the last pitch was ball, tomato head."
Suspecting that the umpire would erupt with anger, the coaches and players braced themselves for Ruth’s ejection. However, the cool headed Pinelli replied, "Maybe so, Babe, but mine is the only opinion that counts." 
Believers need to realize that God’s judgment is the only one that counts and resist the temptation to argue over disappointments. We need to rely on God’s sovereign choices for us regardless of whether they seem popular or not at the moment.
Today’s passage deals with the judgment for the ungodly. Jude knows that not everyone who calls Jesus Lord, or has had a conversion experience, or has prayed the “sinner’s prayer,” or has had spiritual experiences is in fact a true follower of Jesus. One recognizes the true followers by their obedience to their Lord. 
Matthew 7:21 (NKJV) “Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven.
There are those in the church that are quick to say “Lord, Lord,” and know all the church vocabulary, and know all the right things to say, but the actions to not reveal a changed life.
Titus 1:16 (NKJV) They profess to know God, but in works they deny Him, being abominable, disobedient, and disqualified for every good work.
These are the ones that Jude has been warning against. A good portion of the NT warns against these false teachers.
Jude 4 (NKJV) For certain men have crept in unnoticed, who long ago were marked out for this condemnation, ungodly men, who turn the grace of our God into lewdness and deny the only Lord God and our Lord Jesus Christ.
God is well aware of what is happening, He has seen these false teachers, these false Christians, from the beginning of time, and their condemnation has already been laid out against them. They may have fooled the church, they may have fooled all the people around them, they may have fooled even themselves, but they have never fooled God.
And it may seem to many the wicked is winning. This is not a new theme:
Psalm 94:3 (NKJV) LORD, how long will the wicked, How long will the wicked triumph?
The warning has been given to them over and over in the Bible
Jeremiah 17:10 (NKJV) I, the LORD, search the heart, I test the mind, Even to give every man according to his ways, According to the fruit of his doings.
Judgment is coming. The scriptures is quite clear, Jesus will be the judge. He knows the heart and mind:
Revelation 2:23b (NKJV) … and all the churches shall know that I am He who searches the minds and hearts. And I will give to each one of you according to your works.
And Jude tells about the judgment that is coming:
Jude 14–15 (NKJV)
Now Enoch, the seventh from Adam, prophesied about these men also, saying, “Behold, the Lord comes with ten thousands of His saints, 15 to execute judgment on all, to convict all who are ungodly among them of all their ungodly deeds which they have committed in an ungodly way, and of all the harsh things which ungodly sinners have spoken against Him.”
First, let me explain the prophecy by Enoch, we read about Enoch in Genesis 5:18-24. Not to be confuse with the son of Cain named Enoch, but this Enoch is clarified by saying he was the seventh from Adam. So he was a descendant of Seth, not Cain.
Jude is quoting from the book of Enoch, that someone else wrote in the inter-testament period (110 BC?); which is another of the pseudepigraphal, apocalyptic writings of the times. Jude quoting from Enoch (well known in Jude’s day) only affirms the truth of that prophecy and is not his endorsement of the entire book.
Paul quoted Aratus (Phaenomena 5) in Acts 17:28, and he surely did not intend to teach that the entire work was inspired Scripture. Similarly, he quoted Epimenides in Titus 1:12, without any notion that he accepted the truth of the whole work. 
“Behold, the Lord comes with ten thousands of His saints” With the knowledge about Jesus, “Lord” here clearly means Jesus. Jesus is the Judge; it is Jesus that will be coming, again.
1 Thessalonians 3:13 (NKJV) so that He may establish your hearts blameless in holiness before our God and Father at the coming of our Lord Jesus Christ with all His saints.