You’re not the doctor. I take responsibility for the medications I prescribe, you fill them accurately and conscientiously. That’s the deal. If you want to make sure I meant it, please do, but don’t deprive my patients of the medications I have decided in good faith they should take.
I take responsibility for the medications I dispense, you prescribe them accurately and in accordance to evidence-based medicine. That's the deal.
When dealing in situations where the evidence is much more controversial and open to subjective discretion, then we can take "faith" into consideration.