Preaching to the Converted?

This image was rendered as two separate layers.
The first was with the scene minus the fog, and contained inside a glossy cube set to 200, 200, 200.
The second render included the fog prop, and with the scene bounding cube set to matte 0, 0, 0.
Both renders were then combined in paint shop pro 5, with the fog render layer set to lighten.
No other post work other than to add the sig and banner.

Items used;-
(Daz3v1.2.32 to Reality1v25 to Lux0v8)

Sacrament by Jack Tomalin; Contained in a glossy cube (with diffuse set to 200,200,200 for the first render, and set to matte 0,0,0 for the fog render)
Several planes set up outside the Sacrament model to prevent light leakage around the geometry... as shown here... [link]
Mortis For Sacrament by Jack Tomalin
Cyborg Version 4 by DzFire
The Nun by SWAM/Silencer/Sarsa
Reality Fog prop set to amount 3, Rays 3 (rendered as separate layer)

Reality Light scaled to 1% outside the stained glass window; black body = 5061, gain = 1.0
Candle flames from Free Candle Set by John Reilly [link] used inside the top of each visible Sacrament candle; each Sacrament candle set to 0.8 Opacity in Reality. John's candle flames set to gain 0.5, black body 2020
Cyborg V4 Eye.lens converted to light @ 1w with full blue colour 0,0,255. Gain = 0.0016 in Lux

Bloom set in Lux to amount = 0.01 Radius = 0.07

Camera focal length = 30mm
resolution = 1920 x 1200

Render 01;- (shown here... [link] )
1/2sec f4.0 iso 1250
samples per pixel = 6,950
first render time = 11 days 7 hours

Render 02 (fog render);- (shown here... [link] )
1sec f2.8 iso1250
samples per pixel = 2,850
second render time = 7 days 22 hours

Total render time for combined image = 19 days 5 hours

Rendering in Lux used 6.6Gb memory to hold the scene.

EDIT:- There is related info here on creating stained glass and using it with the fog prop... [link]