I think there are some sensible things that you can say under the guise of the Outsider Test, and some things that aren't so sensible. It is something like Russell's The Value of Free Thought in that respect.
I think you have to look at some different epistemologies, like the one that I expounded above, and ask what kind of outsider test you want to use.
If it is just an exhortation to take into consideration that there are other, perfectly intelligent people who don't believe as I do, that's hardly news to me. Being "skeptical" doesn't tell me a whole lot.
The danger here is that the test will be used to establish some strong polemical claims against Christianity on a "hard" reading, but under cross-examination the "test" retreats to its "soft" interpretation.
On the other hand, if someone objects to the "test" that person is told that they are brainwashed and refusing to raise questions about their faith, because they are refusing to absorb the "sensible" point the test makes. The "sensible" point about subjecting religious beliefs to intellectual scrutiny is one that I wholeheartedly accept. That I somehow should think of orthodox Christianity as no more probable that Mormonism when I begin investigating the issue is, in my view, not sensible, basically because I believe in the Decline and Fall of Classical Foundationalism, and I think it requires an artifical neutrality that should not be required of anyone, Christian or not.