Believers distrust atheists because they doubt atheists feel watched by God.

Evidence

At the same time, not all participants reacted in the same way to this task. Intuitive distrust of atheists was significantly weaker among those who expressed low levels of belief in God, and significantly more prevalent among those who expressed strong belief in God. And then we found the smoking gun: the religious intuition that people behave better when they feel like God is watching. That is, religious (and perhaps even some nonreligious) people who equate religiosity with moral conduct and cooperative behavior are the ones who are especially prone to distrust atheists. And this is why belief in God is a powerful predictor of whether or not someone distrusts atheists. — Norenzayan, Ara, Big gods - how religion transformed…, 278

Categorization

• XREF: Directly supports the core analytical claim: the Big God mechanism conditions believers to see only the God-watched as morally reliable.
• QUESTION: This could sharpen the role of the fumi-e: Japanese authorities demanding trampling are weaponizing the believers’ own anti-atheist equation of religiosity with trustworthiness.