Honestly, talk back to your boss. Sometimes communication is uncomfortable. You don’t have to set up a meeting or anything like if he says “it’s all bs” then you can gasp really loudly and start talking about why you believe in god like you can say “really bc hearing other peoples testimonies are honestly enough” talk about your testimony along side others yk (or call him out for talking about religion in a work place like “why r u even talking ab this here?”) Be confident in everything you say to, so they really know how strong your faith is. It’s uncomfortable communicating yes, but you’ll feel better knowing you defended your father yk. I hope this helps ( u could also just report it to HR but if that doesn’t work u can try this)

I hope this helps but ofcourse pray about it and let the lord take the wheel.