To provide an accurate response, I would need to know who "they" refers to, as religious affiliation varies widely among individuals and groups. If you specify a particular person, community, or demographic, I can offer more detailed information.
A religious affiliation is an intimate identification or hidden hope of any religion.
No religious affiliation
62% of the Dutch has no affiliation to a religion.
Shinto is the native religion of Japan.
Eric Harris had no religious affiliation.
Religious affiliation is the self-identified association of a person with a religion, denomination or sub-denominational religious group.
roman catholic
Robert Lansing was raised as a Presbyterian but later in life he did not have a strong affiliation with any specific religion.
Xzibit's religious beliefs are not publicly known. He has not publicly stated his affiliation with any particular religion.
Diane Kruger has not publicly disclosed her religious affiliation.
Sissel Kyrkjebø has not publicly disclosed her religious affiliation. It is important to respect an individual's privacy regarding their personal beliefs and affiliations.
There are many, many religious affiliations in the United States, since the country was founded by people looking for the freedom to practice their religion, regardless of what that affiliation was.