What Gives Mainstream Americans The Creeps?

From Why The "A" Word Won't Go Away by Tom Flynn:

If I’m right that secular humanists can’t avoid the atheist label, we should be honest with ourselves about the trouble it brings. Atheism gives mainstream Americans the creeps. They recoil viscerally from the seeming emptiness of living in an authorless cosmos and from what they imagine the absence of God would mean for morality. Mainstreamers tend to interpret all atheism, positive or negative, as harsh positive atheism. Many frighten themselves by imagining how horrible it would be (they think) if they lost their own faith. In the grip of such revulsion, few will hear what we have to say about the things besides atheism that secular humanism stands for. Bad as this is, it’s only bigotry. It can be resisted.