***Therefore, it doesn’t follow that the victim was shot because he was Catholic. ***
According to the news report I just read, he heard a commotion, walked into the room and asked “What’s going on?” and was then shot.
You provided no reference so I have no idea which news report you just read. According to this article:
A gunman who broke into a staff meeting at a Colorado ski resort ranting about religion asked the manager what he believed and shot him twice when the victim responded he was Catholic.
That's quite specific.