This quest is not available in game.
Speak to High Priestess Laurena in Stormwind.
Your temple wishes you to return to them once again, <name>. High Priestess Laurena in Stormwind specifically. There is much activity in the Cathedral of Light these days, but that does not surprise me at all; so much going on between the Scourge, the Horde and our own problems internally.
Go to the Cathedral when you're ready.