That's a definition of religion?
Try this one: "a specific system of belief about deity, often involving rituals, a code of ethics, and a philosophy of life".
What "big questions of life" are addressed by liberals, especially that are different from the same questions addressed by conservatives? Everything from Pokemon on up (oops, some people do see religious connotations there; let's make it baseball... nope, won't work there either; how about quilt-making... nope, too zen-like) "lends significance to our daily exertions". "Providing a rationale for collective action" can include the PTA. In fact, everything in his definition can equally be applied to the PTA; is that a religion too?