Definition of "dedication" from Wikidata:
expression of friendly connection or thanks by the author towards another person
Nothing in this definition says that "dedicating to" necessarily implies "naming after" (even though naming after can be a form of dedication). A few examples:
- The novella "Strange Case of Dr Jekyll and Mr Hyde " is dedicated to Katharine de Mattos, but isn't named after her.
- The weapon "Molotov cocktail" is named after Vyacheslav Molotov but isn't a dedication to him, as it wasn't meant to honor him, but to mock him.
- The museum Mani Bhavan is dedicated to Gandhi, but not named after him.
- The Dallas Hilton is named after Conrad Hilton, but not dedicated to him.
Now, it's often the case that Christian buildings are named after the saint they're dedicated to (in fact, I couldn't find examples where it isn't the case), but these buildings may have changed names throughout history, and can also have multiple names (e.g. the "Cathedral and Metropolitical Church of Christ, Canterbury" dedicated to Jesus is much more widely known as the "Canterbury Cathedral"). So I guess it can make sense to distinguish between "named after" and "dedicated to" even in the case of Christian buildings.
You could ask on https://christianity.stackexchange.com if you're looking for examples of churches or abbeys that don't have a formal name related to the saint they're dedicated to.
Now, if you fear you might not follow the correct use of these tags on wikidata, why not discussing directly the issue with the wikidata community? You'll probably get more useful feedback, as this stackexchange website has currently very few active users, who don't necessarily participate in wikidata.