Simple vs Complex

I also like more old-fashioned prose and have been criticized for trying to use it in my stories. Now I understand it a bit better.

When you use language in a way that's outside the norm, the reader thinks there must be a reason and tries to look for how that transgression can be meaningful in itself. That's how the Gricean maxims work. Your reader is going, "What did they mean by this?" They think you wrote your sermon in such style because you're trying to specifically evoke a preacher from centuries past, or maybe they even think you're trying to parody sermons. When they don't find such a reason to write like this, it feels out-of-place. It's like if someone wore a donkey costume to work; you would first ask yourself whether they're trying to make some kind of statement, or if they're on drugs or something, and lacking a reason, it just feels like an unnecessary excess.

I have resolved, thus, to only use archaic language when there's a reason: maybe my story is set in the past, or I'm writing something intended to evoke a genre where such language would fit, such as a fairy tale or a political speech.

You also have to consider your audience and the purpose of your writing. If your sermon is written for faithful, dedicated Christians who want a beautiful reminder of their faith, a more elevated and poetic style makes sense. On the other hand, as others have pointed out, such a style isn't going to win over unbelievers or people who aren't sure about their faith. Why? Because it makes church sound old-fashioned, like something that doesn't hake a place in modern life. It's not that they are too dumb to understand the prose. It's rather that archaic writing reinforces a preconception about religion in their minds that is contrary to your goal of inspiring people and calling them to your faith.

Another issue is that too-convoluted phrasing might be too hard to follow to read well. Even if you are being more flexible and poetic with word order, jumbling it up too thoroughly just makes it harder to follow logically and not more beautiful. There needs to be a logical order in arranging your ideas.

A guy in my fiction writing class in university, like me, liked trying to write in a more archaic style. The class gently teased him when one of his stories had a character attend university "for the study of computer science" instead of just "for computer science." The problem was that his somewhat more archaic phrasing seemed ill-fitting with something as modern as computers, and even if it wasn't, it's unnecessarily wordy. It's annoying because it takes longer to say or read without adding anything meaningful; if you say someone is going to university "for computer science," it's easily understood that they're studying it. Plus, this particular sentence in the story is just giving a mundane detail about a character; it does not need to be beautiful. More stylized prose makes more sense when writing an emotional passage.

Still, I don't want to see 19th-century styled prose die out or become too complex for people. I think it is beautiful. But there is a place for it, and I think the best we can do is try to extend its place in moderate and inoffensive ways.

Could you maybe post some a paragraph of text you find to be ideally written, and we can break down what is aesthetic about it and see what we can use from it?

For example, one small thing I've noticed about older prose is they place descriptive phrases differently. They might say, "I am day by day working on it" instead of "I am working on it day by day." And that placement of "day by day" is a subtle thing you can consider in your writing that doesn't stick out too badly, yet imparts some old-fashioned flair and gives you more options in how to structure your sentences.