Working class seculars are more ‘religious’ than middle class seculars. But they are still more secular than the religious middle class.
For example, based on questions on the general social survey, the following percentages identify as atheist/agnostic, don't identify as such but don't "know God exists", and "know God exists", are shown below:
Religious, No College: 1%-10%-89%
Religious, College: 2%--19%-79%
Secular, No College: 13%-48%-39%
Secular, College: 32%-51%-17%
The GSS also dramatically illustrates the unwillingness of most people whose beliefs seem to fit the definition of "agnostic" to accept that self-identification.
About 18% of secular people with no college have religious beliefs that the Bible is literally true and consider themselves religious fundamentalists, a sure fit for the apathetic rather than atheistic category (compared to just about 2-5% of college educated non-church attenders). But, most people who rarely or never attend church, even among those with no college education, are genuinely non-believers or doubters, as well as being non-attenders.