Now for something controversial: The name of your parish.
Catholics are at odds concerning the exact name of their parish. Let us take, for example, the name of this parish: St. Sebastian. This is not St. Sebastian’s Church. To begin with, we are part of the Roman Catholic Church, not St. Sebastian’s Church. We are properly known as St. Sebastian Parish. The church (little “c”) is the building in which we have Mass. The Church (with a capitol “C”) is the greater Catholic Church. So if you were going to say (or print) St. Sebastian church (with the little c) you mean a specific building on the campus. If you say it with a capitol C, you are talking about a schism. (Okay, that may be a little bit extreme, mostly said for comedic effect, but you get the point.) The point is this is St. Sebastian Parish.
And it is NOT St. Sebastian’s Parish. (I am sure I’ll get some push back on this.) He doesn’t own it. It is named after and enjoys the intercession of this (really cool) saint, but it is not his property. Sacred Heart Parish is not “Sacred Heart’s Parish” nor is Sweetest Heart of Mary Parish in Detroit named “Sweetest Heart of Mary’s Parish.” Your local elementary school is not King’s Elementary. It is King Elementary. So this parish is properly known as St. Sebastian Parish.
So, these work:
St. Sebastian Parish (everyone and everything connected to this place.)
St. Sebastian Roman Catholic Church (if you want to specify to whom we belong)
St. Sebastian church (if you want to specify where something is taking place at the parish)
St. Sebastian Parish Church (if you want a formal title for that building.)