Wish us the best all you want. I'm okay with that. But if you believe in a god who is almighty and entirely good and nothing happens without him saying so, you're praying to the one who caused her cancer according to your belief. It's no different than asking your captor for mercy while he demands ransom. Instead of praying to your imaginary friend, do something that actually does some good. She's strong willed and incredibly stubborn and hasn't given up yet. Keep the encouragement going her way. But leave the homicidal maniac worship out of it.

Sorry to hear. I had the same situation in 1993. I always took the 'praying for you' as best wishes, or they are keeping good thoughts for me or keeping me in their mind. The specific phrase or ones like have no meaning for me, so I take them as the people care about my situation. Let it be.

I’m so very sorry that your mom is sick. All grief sucks, but grieving in advance while dealing with a serious illness is twice as stressful. Do self-care whenever you can.
Hoping for the maximum comfort for your mom.

I hear your pain and wish peace for your mom.

Nothing fails like prayer.