I'm not religious so I switch off to those sort of posts. People who are religious will read and vote. People who aren't will move on. Preaching to the converted is the phrase that springs to mind.
LFBs comment was interesting as I often write about politics. Some of my posts are probably controversial, and shock horror, contain swearing. But as dp says, a regular readership knows what to expect, so unlikely to be put off. The issue is, will a post like that attract new viewers? And the answer is only if they are religious. But that's probably the readers you want anyway.
Oddly I have been planning a post about religion and never got round to it. I guess it's too far down my priority list.