Polarizing filters can be helpful, and their effect cannot be replicated well in post-processing. However, a polarizing filter would not help in this church scene as the light is diffuse, and they require directional light to function, with the maximum effect at 90° from the source.
They’re usually used to:
- Remove reflections from water, allowing you to see into the water (cannot be replicated at all in post-proc).
- To darken the sky.
- To remove “sky white” light reflected off of foliage to bring out more color.
Here’s an example from the woods from a few days ago.
It cut out the harsh light reflected from the foliage, which lowered the dynamic range of the scene a bit. The moss looks less sky-white and more its natural color - a strong green tinted yellow by the setting sun. Whatever bits of sky are visible are darker when using the polarizer as here I was about 90° to the sun.