Actually, here’s a better challenge for the LDOS and it’s adherents.
If you’re certain god exists and you’re convinced by the power of prayer, stop all the posturing and protesting and fall back on your faith. Just pray to god and ask that sunday sailings be prevented.
It’s a win-win situation for you. If, for whatever reason, Sunday sailings don’t go ahead you can claim that as “evidence” for the power of prayer and a clear sign that your god is there watching over you. On the other hand, if Sunday sailings are introduced you can claim that god moves in mysterious ways and that it’s all part of a divine plan to bring you closer to god through adversity – or some other such rubbish.
Go on, go for it!