Behind the door (not very interesting).

[Azazel]

This is what is behind the door with the gate in front of it, at the top of the room were the murals of the sarafan brothers are, at the birth of Kain, in Soul Reaver 2.
http://home.wanadoo.nl/door.zonnetjes/Behind%20the%20door.JPG
Note that the extra Raziels are just to show that he's falling and you can turn him around.
BTW I came here because I tried to open the door, but I got hit by one of Moebius' followers.

[Vampmaster]

That's what happens any time I use a walk through walls cheat and fall off the level. Sometimes the background's sky coloured.