Before this goes any further someone should explicitly state their
definition of a religion.
This is from Microsoft Bookshelf:
re·lig·ion (rī-līj¹en) noun
Abbr. rel., relig.
1. a. Belief in and reverence for a supernatural power or powers regarded
as creator and governor of the universe. b. A personal or institutionalized
system grounded in such belief and worship.
2. The life or condition of a person in a religious order.
3. A set of beliefs, values, and practices based on the teachings of a
spiritual leader.
4. A cause, a principle, or an activity pursued with zeal or conscientious
devotion.
In my opinion Skepticism would certainly not apply as a religion under the
first definition, or the third (unless you really stretch what is meant by
spiritual leader, and even then I can't see it fitting). The second
doesn't fit, and that leaves the fourth. The fourth definition could
certainly apply to at least some skeptics. I think that a modification of
definition three that simply leaves out the requirement that there is a
basis on the teachings of a spiritual leader, would be come closest to
fitting skepticism