Jude records here a very ancient prophecy. It is a prophecy that was made by Enoch before the Flood.
Yes believers too: we all appear before Christ in judgement, but we won't appear with horror and fear and misery. We will be given a view and a glimpse in the day of judgement of all our sins everything we've ever done and committed. Just like the unconverted, but it won’t for us be a public view. We will see these things and the seeing of them will just cause our hearts to well up in such thankfulness and praise that we are cleansed and we are forgiven and Christ has taken all for us and he takes us under his wing and takes us aside. So to see our sin will not for us be an experience of horror and shock and shame, but of amazing gratitude and wonder that all this has been atoned for. But all will appear.