I thought I was qualifying this as genuine love expressed through prayer. Assume there are limits of what they can do for support to you, other than prayer, that that is the most that they can humanly offer. Are you still ungrateful for their love and concern that they express through prayer, which they believe can help on some subtle level, where they feel powerless otherwise? Isn't them praying for you, them supporting you in what ways they believe could help you? Isn't that an expression of their love for you?
For someone to sincerely say they will pray for you, is their way of offering support. Do you just reject their gesture of support to you because you think prayer is silly? Or might you say thank you in response, acknowledging they are offering a gesture of support in a way they know how under the circumstances, even though you have the opinion that prayer is nonsense?
Praying is doing something. They don't consider it a waste of their time. They may do that in addition to helping where they can, or if they can't do anything but pray, that is still support and doing. Isn't it?
But they believe in their God. You don't believe in pink unicorns. Theirs would be a sincere gesture, while yours would be a mockery of them, essentially slapping the spoon out of their hand as they try to help in what they believe helps, because you think their beliefs are stupid.
I think the question of this thread boils down to, can you see it from their perspective and recognize it as an expression of sincere love for them coming from their beliefs, even when you don't agree with them? It's sounding like your answer to this is no. Are you saying you can't see beyond your beliefs to the intention of the person offering that for you. Is that accurate?