Do you believe it at all?
I am struggling with this one.
Is “completamente” really a good translation for “at all”?
It is a big difference between “Do you believe it all” and “Do you believe it at all”.
I found only “I would not succeed at all” = “Non ci riuscirei del tutto”
I would have said “Lei ci credi affatto!?” kind of meaning “Do you honestly believe it!?” I too am not happy with “completamente” here although I see it means *altogether and *entirely which makes the translation more acceptable.
It seems like the speaking tone would convey whether it was “all” or “at all”. Just written though it would seem like “do you believe it all, completely, every word?”, sort of opposite of “do you believe it at all, maybe even a little”. I agree that Lei ci credi affatto! and Do you honestly believe it? seems like a clearer combo all around.
The Italian sentence does not match the English one, but your sentence is not working either.
“Affatto” is not used in this kind of sentences, but I see the reason for the confusion, because it is used normally in negative sentences, where it means “(not) at all”.
Actually, finding a good idiomatic translation is not easy.
“At all” here means “even a bit”. So if we want to convey that, we could use
“Ci crede, anche solo un po’?”
This is ok, but it is not an everyday sentence as the English one.
I would probably go with “Ci crede davvero?” or “Ci crede veramente?”
Also, remember “Lei” works as third person even when it is used as a second person pronoun.
“Ci crede davvero?” I like very much. It says it just right;-)