Blender, Cycles, a few small tweaks with GIMP afterwards.
2.7M polygons (5.4 tris).
All mats are procedural except stained glass window picture by Eusebius(Guillaume Piolle) - taken from Wikipedia.
Sunrays done with Sun Beams node.
Had to render this on CPU (4+ hours), since for some bad reason CUDA crashed every time.
And God bless Cycles denoiser!