“Why do we sing the line “world without end” yet talk about Jesus and judgment day? Do these not conflict?”
This is a good question. The simplest way to answer it is probably to say that judgment day inaugurates a new world that will never end. Revelation promises, and the rest of the Bible points toward, a (re)new(ed) heaven and earth where heaven and earth are united and God’s will is done in on earth as it is in heaven. Instead of rescuing us from the world, God recreates it to be as it was originally intended to be. It is that world that goes on forever. (And in that world we go on forever in resurrected bodies that are not subject to death or decay. The idea of disembodied souls comes from the Greek philosopher Plato, not the biblical witness). This understanding has a lot of ramifications for how we view the world we live in and it means that the goal is not to escape from the world, but to be part of what God is doing to renew it.