America's fastest-growing religious group is also one of the hardest — and costliest — to reach: the "nones." Why it matters: Religiously unaffiliated Americans now make up a large and growing share of the electorate. But without church-based networks, they're significantly more expensive for campaigns to reach and mobilize. "Nones" are geographically and socially dispersed. Campaigns must rely on costly digital ads, canvassing and persuasion to reach them. By the numbers: A record 29% of Amer