Your whole setlist does not have to be in the same key. In fact, sometimes that makes for a really boring sound. Be mindful of the flow from one song to the next when picking keys. Sometimes, bumping a song to a less comfortable key (not 5 whole steps up) to make sure it flows well out of the previous song and into the next song is worth having to work a little harder at the vocals. Try to pick keys that play nicely together. Sometimes it works well to have a few songs in one key and the rest of the songs in another. If you are transitioning between keys that don’t play nicely together, work on your vocal transition. The goal is for the congregation to not feel like you’ve put the brakes on.