It is entirely placebo. Anyone arguing otherwise lacks the most basic understanding of science.
But, we simply don't have any way of measuring whether or not medicine is causing a placebo effect via the subconscios or not.
What are you even talking about? The placebo effect can be measured extremely easily. You have seriously never heard of a randomized control trial? The entirety of modern medicine is based on comparisons against the placebo effect.
The basic problem here I think is the different mindset, and the key word is presupposition.
For people who have a religious, faith-based understanding of the world, belief is what comes first and underpins any evidence. If the evidence doesn't fit the belief, it won't be accepted. This is why you'll never be able to convince a religious person of the veracity of an argument by using logic, facts and science - they simply won't accept the tools unless they build on the existing foundation.