OUTSIDE are
OUTSIDE means not allowed in the new Jerusalem, THE CITY. From the list which follows, one understands that OUTSIDE is the lake that burns with fire and brimstone (Revelation 21:8).
By Jewish law, DOGS are unclean animals (Leviticus 11:27-28). 'DOGS' also is a term used for impure individuals (dirty robes versus previous verse). They are listed in Philippians 3:1-2-16 right next to evil workers and falsely circumcised individuals. In other words, they are fakes.
SORCERERS are enchanters with drugs. SORCERERS are on 'the list' of those who are scheduled or chose the lake which burns with fire and brimstone (Revelation 21:8).
If we have received training as a child (Proverbs 22:1-6-16), our conscience will tell us when we are doing IMMORAL deeds. IMMORAL PERSONS also are on 'the list' (Revelation 21:8).
MURDERERS are emulating one of the traits of the devil (John 8:31-44-47), and as such are not of God. They won't get anywhere close to the new Jerusalem. 'The list' (Revelation 21:8) also contains MURDERERS.
IDOLATERS by definition are those who do not WORSHIP GOD (verse 9) exclusively. In fact, if one tries to have every angle covered and worship GOD and other prominent gods (self, wealth, notoriety etc.), it cannot be done (Matthew 6:24-25). IDOLATERS are in 'the list' (Revelation 21:8).
This phrase is even more emphatic than the 'all liars' in 'the list' (Revelation 21:8). It shows that these people don't just lie by accident, but rather enjoy LYING. How sad, but nonetheless, this must make their father, the devil, quite happy (John 8:31-44-47).
After this ugly verse, we come to the sweetest invitation ever given in Revelation 22:16-20. The Spirit chimes in with the bride, the eternal new Jerusalem residents, to invite you (verse 17) to "COME".