[Morrigan herself isn't religious, but she takes a healthy interest in both the teachings of the Chantry and the lore of the Dalish. Who's to say which is right?]

'Tis a specific culture's set of gods. The elven one is the only one I know to have multiple gods rather than a singular one, so, in my experience, 'tis only used to refer to them, but if these are different gods the term could be used just the same.