De Botton, in his attractive comments about Yom Kippur, regrets the fact that secularists do not have a time of year when they can all acknowledge the faults of the past year and try to patch up quarrels — but surely they do: It is the post-Dickensian observance of Christmas. Many who realise the extreme historical unlikelihood of Jesus having been to Bethlehem, let alone having been born there to the accompaniment of angel choirs, see the point of Scrooge’s conversion.Of course, not all those who are both irreligious and who celebrate Christmas and the season leading up to it actually attend a service devoted to the holiday's celebration, but those who attend church once during the year are presumably doing so mostly on Christmas or Christmas eve (it would be optimal for one of the cutoff response to be "once or twice per year" to catch Easter as well, but we work with what we have).
As it turns out, just under one-third (31.9%) of secularists (I use this term not in a functional sense but as it relates to ideas about the existence of the supernatural or lack thereof) can be found in a sanctuary in late December. Looks like the remaining two-thirds, who constitute about 5% of the US population, are de Botton's target market. It's a niche audience, but hey, in the restaurant industry, that's doable.
GSS variables used: YEAR(2000-2010), GOD(1-2)(3-6), ATTEND(0-1)(2-8)