I run a Discord "server" for a Minecraft server that I run, with about 130 members. I wrote a bot with a language filter, and I don't find moderation to be that onerous. In fact, recently people have been applying to be moderators, and we (there are two other moderators) keep declining because we don't need any more. Maybe it's more difficult for a Christian site?
I dislike Discord, though. It's not really private, and while it's called a "server", it's really more like a Docker instance or something like that. You don't have full control over it (no access to the underlying system). That's why, even though I'm a member of some Christian chats on Discord, I wouldn't recommend using Discord for this (or in general).
I tried switching it to Internet Relay Chat. I.R.C. definitely more difficult to set up properly, but it's well-documented and it works. However, everyone was already embedded in Discord, sadly, so no one really used it. I think Element is a more up-to-date option for I.R.C. with some extra features like chat persistence.
I loved the chat here, though. Forums are nice for discussions, but chat rooms are much better for information conversations and meeting people.