I'm a Christian and, oddly, don't suffer from the same existential dread as most admit any more, but I used to be consumed by it.
The simplest way I could say it is this: once you are shown what is behind the curtain and you place your trust in the one who's running the show then dread gives way to overwhelming peace. That's what happened for me and I guarantee that anyone who seeks the same true God will find the same peace.
Easy to dismiss, I know, but I guarantee it's true. Odd, eh?
Part of dealing with your existential dread is accepting the fact that you're right to be afraid, but not for the reasons you first think. This will be a bridge too far for some, but a discerning reading of this could be the catalyst some need: https://www.blueletterbible.org/Comm/edwards_jonathan/Sermon...