My grandma passed away this morning, and I kinda feel like a hypocrite.

First off, sorry to hear that. Secondly , I am on the same page. I have my ideas and theories which happen to be the same as yours . And like you, I know there is a time and place to voice them. And one someone is using theirs to comfort you, it's a time to show gratitude for their effort and not open a debate.

It's like when someone says, "God bless you" after you sneeze. Just say, "thank you". They weren't preaching religion, they were just being kind

Ironically I'm Christian and I guess we never did that in my family so I never picked it up as a habit. Of course I'm starting to do it lately just because so many others do it when I sneeze.

It means health, or good health.