Key Points
1) God loves us and wants us to live in His presence eternally in a new holy city, the new Jerusalem. It will be within a New Heaven and New Earth.
2) God cannot and will not be around sin. This means that the city, the the New Heaven, the New Earth, and all of its inhabitants must also be made holy.
3) God sent his one and only Son to be a sacrifice to pay the penalty for sin for those who follow Him and for all creation itself.