In Reality, Most People Who Say They Are Affiliated with Some Religion [View all]
are nominalists. A nominal Christian, or Muslim, or Zoroastrian, for that matter, is someone who identifies with that religion by name, but who is not a serious adherent to the beliefs and rules of the religion. Such a person does not actually practice the religion they name. Most people, for example, did not know that Freddy Mercury was a Zoroastrian of Iranian descent. A nominal Zoroastrian.
"Nominal" has its roots in the Latin word "nomen" or "name." So, a nominal Christian is a Christian in name only. It is someone who, by reason of upbringing or other influence adopts the name of Christianity as part of his or her identity, but who does not seriously study or follow the tenets of that religion.
When people are polled about their religious affiliations, most will say that they are followers of whatever religion they grew up with. Many of those, probably a fairly large majority, do not attend regular services or really have much to do with the church they identify. If asked, they could not tell you much about that religion's doctrines. It is simply another "name" they associate with themselves. The name is merely an identifying token.
This is true, really, of all religions, denominations, and sects. Far more people identify as followers than actually adhere closely to the doctrines of whatever religion they name. They see no contradiction in this, since they have the same nominal relationship with their nation, state, political party, fraternal group, or other identifiable groups. Someone who has never voted in a single election might well identify as a Democrat or a Republican, even though they don't act in any way on that.
Nominalism drastically skews polls. We should not think that because some 80% or 70% of Americans identify as Christian or even as some other religion, those people are actively involved with that religious group or even know much about it. Most, in fact, are not, as the parking lot of almost any church will demonstrate on a Sunday morning.
We should not put much credence in such polling numbers. They have little to do with the doctrines and values of the churches and other religious groups that are named. Most who are polled are only nominally associated with those religious groups.