I have a two part question. During the Sunday School class I teach, I had a person state that there will be unsaved individuals living on the New Heaven and New Earth based on Rev 22:14,15. I feel that the “outside the gates” refers to the Lake of Fire” I also explained to this individual that Satan will be permanently in the Lake of Fire and thus being the author of sin, who would tempt mankind to sin? Was this answer correct? My second question relating to this is: would it be possible for man to sin without the presence of Satan and his demons, for example could Adam have sinned if Satan had not fallen?
Let me answer the 2nd question first. We don’t know for sure because Adam was the first man and had experienced no prior temptation. But Ezekiel 28:15 says Satan was blameless until he began sinning and there was no one to tempt him. It could have been the same with Adam.
With that background, Rev. 21:27 says nothing impure will ever enter the New Jerusalem, but only those whose names are written in the Lamb’s book of life. That means only the redeemed of the Church will be allowed there.
But on Earth there will be sinners, because those who live there will be believers who survive the Great Tribulation. They’ll be in their natural states with a sin nature and will bear children in their own likeness. Some of the children will choose to allow the Lord’s death to cleanse them of their sins. These are referred to in Rev. 22:14. But others won’t, and although Satan will be bound all during that time, natural man with his sin nature will still have a tendency to sin and many will succumb. They are the ones of Rev. 22:15.
In all this, we have to remember that all of Rev. 21 and much of Rev. 22 chronologically follows Rev. 20:6. In Rev. 20:7 -15 John is simply carrying his comments on Satan and the judgment of unbelievers to their conclusion before returning to the beginning of the millennium provide more detail on the New Jerusalem (Rev. 21) and new Earth (Rev. 22) during the 1000 years. Also from the dimensions John provided on the New Jerusalem, it’s clear that it won’t fit anywhere on Earth but probably orbits in close proximity to it (It’s 1400 miles square and 1,400 miles tall.)
The New Jerusalem of Rev. 21 and the city of Rev. 22 are different places. A more complete description of the city can be found in Ezekiel 47:1-11, 48:8-22 and 48:30-35, where its new name is given as Jehovah Shammah, which means the Lord is there.