yeah, that's a nightmare; sharing a monitor mix is miserable, especially if players are relying on it for their entire instrument sound (as opposed to having their own amps and just suffering with a shared vocal monitor mix).
until such time as there is actual professional monitoring where everybody gets their own mix, you just need to bring a bass amp. (do it in the spirit of generosity, taking your bass out of that shared monitor will make everybody else happier too.)
even if you make it a small one (like a decent 300w head pushing a little 1x12 cab) and set it up angled to point at your ears, you'll be so much happier. don't let clueless church "soundguys" tell you that it's bad because it'll make things louder, because if you do it right it won't! in fact it could make things quieter, by not crowding into that one monitor mix and making everybody else turn up more in there trying to hear themselves.
you could even put this little bass cab in front of you pointed back, like it was a monitor.