Verses 17 - 19: "But, beloved, remember ye the words which were spoken before of the apostles of our Lord Jesus Christ; How that they told you there should be mockers in the last time, who should walk after their own ungodly lusts. These be they who separate themselves, sensual, having not the Spirit."
In the Bible, separation is usually spoken of as a necessary desire of the Christian to please our Lord Jesus Christ, but it is not so in this case. If you read the preceding verses in the book of Jude you will see that these are people within the churches. They have separated themselves in the name of godliness and righteousness but as stated in our quoted verses, "having not the Spirit." Meaning they are not being led of God. They "walk after their own ungodly lusts." Meaning whatever makes the flesh feel good is considered Godly to them. Throughout the New Testament whenever church type services are mentioned, preaching is always the main part. Today many churches do very little preaching and spend most of their time entertaining each other. I met someone this week who attends mid week services at a church. When asked what they do, the reply was that they get together at every service and eat and fellowship. This was not just for that service but every mid week service. In the book of Acts, Paul once preached so long that a young man fell asleep and fell out of the window and died. The Lord performed a miracle and allowed Paul to bring him back to life. (Acts 20) Maybe if churches spent more time preaching and paritioners spent more time listening then more people could be saved from death and hell. In the Bible very little is ever mentioned about the singing, praising and worshipping, or abundance of signs and wonders in any church type services. These things are not of themselves bad, but it was not the focus of the service and when the people left they pondered the Word of God which they heard from the preacher of God and not the abundance of high energy music and praising. People desired to be changed and have more than the flesh could give them and accept what only God could give. This desire was lost when we as God's saved and forgiven children wanted to be patted on the back while participating in our sins instead of admitting our wrong doing and changing it God's way known as repenting. This is the mocking of the last times against God's tried, true, and perfect ways. Notice what God expects of His church in the following verse from Revelation. The beginning of the book of Revelation starts with letters to seven churches. Near the end of these seven letters God mentions his main theme and desire for the churches in chapter 3 verse 19.
"As many as I love, I rebuke and chasten: be zealous therefore, and repent."
Don't try to make God and His church try to fit you, but through His grace, repent and let God mold us to fit Him and His church.