Think about how many musicians would not be able to play to an audience were it not for the church. Think how many would lose a living wage, or at least a supplementary wage were it not for the church. Think also about the congregations, some who just want music and are willing to pay for it to a degree and whose demands are not that great nor is their musical sophistication at a high level. They don't know a yamaha from a casio or a danelectro from a fender. You have these people playing and in the choir as well. They might be satisfied. They aren't going to pay a lot more money to personnel/for equipment and they aren't gonna listen to very much talk about it.
Many of them think that their musicians can play anything without practice because that is what they have seen. I mean they really think that. If they hear a lot of noise about it, they think the musician is just being hard to deal with. I know so well because I thought the same way,(before I learned to play in my senior years) and still do to a point, according to the musician.(not beginners) My daughter, who is a very good musician and makes a living at it shocked me one day by saying that she really didn't like to play for people off the cuff sometimes. She said, people think musicians can play anything. I said Duh?
For every church where you find a well organized, professional type ensemble, you'll find a hundred as I described above. They won't change. Do the best you can. If the minister and congregation are satisfied, you're flogging a dead horse.
Sometimes a musician can feel stunted in their growth in certain situations. If they are being stunted, they would have to consider leaving for that reason, no hard feelings.