I gotta say I think the t-shirt is full on, but have no problem with the coasters. In your own home, what is wrong with expressing your own beliefs?

My daughter has a t-shirt that has an image of the Blessed Virgin on it, with the inscription "Mary is my homegirl". Personally i think it's a great shirt, but we have had conversations about where and how it's appropriate for her to wear it - it's difficult to explain to a 15 year old that there's a difference between edgy self-expression and deliberately causing offence to strangers - maybe even nice old ladieslike your nan. And is that a line you really want to cross? It's an important conversation to have, i feel, even if she doesn't always agree with me.