Is a person marrying into the Swedish royal family required to profess a specific religion (or lack of one)?

Or lack of one? That would be a novel concept indeed! Most royal families are very religious - I can't imagine why anyone would suppose they would be required to not have one. I know they are not required TO have one, but they would never be expected to not have one in order to be a member of the family. There are no restrictions for the most part with the exception of Roman Catholicism in the british royal family - that is not allowed. The monarch can not swear allegiance to the Pope.