From a part of my Introduction to The End of Christianity:
When Christians ask if I have taken the outsider test for my own “belief system,” I simply say “yes I have, that’s why I’m a non-believer.”
They'll ask if I am equally skeptical of my skepticism, or whether I have subjected my non-belief to non-belief, or my disbelief to disbelief. These questions express double negatives. When re-translated they are asking me to abandon skepticism in favor of a gullible faith, for that’s the opposite of skepticism—something no thinker should do. Even if having a gullible faith is desirable, which faith should we be gullible about? And how can we decide between these faiths? The bottom line is that skepticism is a word used to describe doubt or disbelief. It doesn’t by itself represent any ideas we’ve arrived at. It’s merely a filter we use to strain out the bad ones leaving us with the good ones. So we cannot be skeptical of doubt unless we think doubt is inherently wrong, which would leave us with mere belief in belief.