What's a cunning discerning faith when it's at home?
I must apologize but I don't understand your question. I can try and explain the Buddhist concept of cunning discerning faith but I don't know what you mean by "when it's at home?" I'm sorry.
Cunning Discerning Faith in the Buddhist tradition is held to have been stated by Shakyamuni (The Buddha) in the Kalama Sutta
. A tranlation
that is the first one to come up on Google. Different traditions and different schools interpret this teaching differently but I will quote Shakyamuni from the translation I found that I think sums up the point of the Sutta:
So, as I said, Kalamas: 'Don't go by reports, by legends, by traditions, by scripture, by logical conjecture, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, "This contemplative is our teacher." When you know for yourselves that, "These qualities are unskillful; these qualities are blameworthy; these qualities are criticized by the wise; these qualities, when adopted & carried out, lead to harm & to suffering" — then you should abandon them.' Thus was it said. And in reference to this was it said.
Now, Kalamas, don't go by reports, by legends, by traditions, by scripture, by logical conjecture, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, 'This contemplative is our teacher.' When you know for yourselves that, 'These qualities are skillful; these qualities are blameless; these qualities are praised by the wise; these qualities, when adopted & carried out, lead to welfare & to happiness' — then you should enter & remain in them.
The quick interpretation of this passage is that one should test an idea to see if it leads to good things. If it does, one should have faith in it but if it does not then one should not have faith in it. I think logic, tradition, inference, analogies and the like can be useful in making this determination but one should not believe something just because it satisfies some or even all of these qualities but rather one should consider whether an idea leads to good or to bad. A modern concept in western Buddhism would likely be that one should not have faith in something because it is in the dogma but rather one should develop faith through the use of study, practice, contemplation, and meditation and through that discover what of the dogma is correct and what of the dogma is incorrect and what truth there is in the dogma. I can give specific examples if requested to do so.