So I'm supposed to guide light of Meridia through the temple. The deity has stressed how cool and powerful she is, but she didn't even manage to open the doors for me:
You can see the quest path indicator guiding me behind that door. What I really need to do is to fix the light crystal on that crystal:
But there's no way to get there, so I assume I need to get through the door. Maybe Meridia forgot I can't fly?
Best Answer
Climb up the stairs and go back to the first pedestal you activated in this room, and look towards the one you need to activate (shown in your second picture, this is just to help orient yourself for the following directions). Then turn around and walk through the open iron door on the same level as you.
After going through the doorway, you will go through a short tunnel that turns to the left and opens up into a room. Cross the room and you will see a wooden door with a dead bandit sitting in front of it (there is some loot here and the door is booby-trapped), and to the left there will be another tunnel. Enter the tunnel, but watch for a tripwire soon after you enter. After the swinging axes there is a lever you can use (I forget exactly what it does) and you can exit the tunnel onto a walkway enclosed in metal bars. navigate through this walkway and you will end up on part of the walkway that is not enclosed and is next to the pedestal you need to activate. You can now just jump from the walkway to where the pedestal is an activate it.
Jump back to the walkway and make a left and follow the walkway to a broken part. Jump across and go through the open iron doors and through the tunnel. Then go up the stairs to the right, through the doors at the top of the stairs and into the tunnel. The tunnel will exit at the final pedestal you need to activate to open the locked door from your first picture.
If you are confused by any part, here is a video walk-through, and watch out for corrupted shades.