I am not certain who all is allowed in the Temple of Mystra, but the greeting is as follows when I attempted to enter as my Hexblade.
I believe it also does not allow Bards in, which is probably understandable.
Perhaps the better option is to change that line to not relate several of the Arcane Caster Classes that are not able to enter.
(Bard, Monster Hunter, Hexblade)
Edit: I actually misread the conversation somehow. And thought the "Dost" was "don't/Do not" And I thought I was just getting the generic greeting for a non-magical character.