I agree that faith is not quantifiable. However, there are different means of determining the veracity of items of faith. For example, in a murder we are asked to have jurors convict the accused only on the basis of "beyond a reasonable doubt." (Doubt being the opposite of faith.) In other words, you must have an extremely strong belief in the guilt of the accused in order to convict him.
However, you cannot "view" the crime since it is a past event.
What you can do is assemble evidence that helps reassemble the events of the crime. For example, I was surprised that Scott Peterson was convicted, because they really had so little physical evidence. Apparently, what they did have removed all but the most unreasonable objections.
It was hair, phone calls, girlfriends, cement, actions, etc., that enabled the jury to reconstruct a likely scenario of what happened.
Similarly, both evolution and ID must appeal to evidence that they can assemble to support their contention. Both are striving to show that the assembled evidence best supports their case.
What is the evidence that they use is the first significant question. The second significant question is "what is the counter-evidence?"
Reasons for and reasons against.
It's how we'd convict a criminal.
How does one measure evidence for design? What are the objective criteria? There aren't any. It's entirely subjective. Therefore, ID cannot be considered part of the scientific realm.
That evidence is "master control genes" which are particularly underscored in the discovery of eyelessness evolving concurrently among phyla - especially vertebrates and invertebrates. (Gehring, et al)
Some of the mathematicians (Wolfram, Rocha, etc.) who have entered the debate have suggested the correct formulation is more like autonomous biological self-organizating complexity - which is based on the von Neumann cellular automata model.
Nevertheless, if the CA model is correct it must begin with an algorithm at inception (basic rules for self-organizing complexity) which in itself would be proof of intelligent design.
In addition to this difficulty with happenstance, evolution so far has no explanation for the rise of semiosis (language, encoding/decoding of DNA or RNA), autonomy and complexity (by whichever means you choose - self-organizing, Kolmogorov, physical, functional, specified, etc.).
My personal favorite though is that evolution has no explanation for the rise and continuance of successful communications (Shannon, information) in molecular machines.
In the absence of an explanation by materialists, the Occam's Razor choice is intelligent design.