Religion is a legally protected class in the US, and the fact that a boss would willingly want to discuss, much less debate it with a subordinate opening the business up to much unnecessary liability is a red flag at least for stupid leadership.

Worst case scenario, the boss is trying to discriminate based on religion, and trying to find out more about the subordinate’s personal beliefs. Best case scenario, boss is for whatever reason curious, but displays lack of knowledge of labor laws and best practices (in the context of asking to discuss with a newbie who they have no prior relationship with).

After a working relationship had been established, I could see religion as a as a casual topic being reasonable depending on how what their relationship is like, but as an introduction? Forget about it.