It depends on your goals to what you should do.
If your aim is to make content specifically for other Christians, about your beliefs and religion - then just make that your niche. There are lots of other Christians out there who'd surely love to listen to your content, especially if you can make it new and interesting when compared to other Christian YouTubers. The key is to be very careful about how you target your content and where you draw people in. If you're advertising your videos externally, do so in communities that are already entirely Christian - things like politics, faith, etc, attract a lot of controversy when shown to people with differing beliefs. Do the same when you make searchable videos too, try to make them things other Christians would be searching for not general things that people who want to argue over beliefs will be searching for.
If you just mean making videos about another subject while also being a Christian, then I think it really depends on the subject to how often you should mention it. If you're like a gaming channel for example, people don't really come there to hear about politics, or spiritual beliefs, or anything that requires a while lot of thinking - they come to get entertained, so while it's okay to mention it I wouldn't suggest talking about it too often.
Also, if you do get any nasty comments from people with different beliefs/ideologies, then my best advice is simply to delete those comments and not react to them. I see a lot of political, spiritual, and other more controversial type channels digging themselves into a hole by replying to the hate and then starting long debates in their comments. Just defuse the bomb before it goes off by deleting the post.
Also, if you do want to attract an audience outside of just Christians, but still want to talk about your faith a lot (perhaps you'd like to introduce new people to the faith etc) then my advice is to think of it like you've got a room where 50% of people already are behind your ideas, and 50% are completely opposed - your goal at this point if you want to captivate all their attention is present things in a way that sits well with both sides. The way I've done this when dealing with slightly more controversial subjects in my own videos is simply by explaining why I personally choose to believe, do, or think about things a certain way - and then follow it up with a little disclaimer saying that people shouldn't just take my word for it and should go with what resonates with them on a personal level - if they believe my advice, take it, if they don't, then don't take it. Just a little disclaimer like that goes down pretty well with a lot of people who'd otherwise not want to hear your side of things.
