Folks in religions usually have a moral code and or can help cover for fellow members when things get tight.

People may be discriminated against on the basis of race, gender, age, religion, or sexual orientation - these are protected categories. 

I'm Muslim; my religion prohibits dealing with interest; either directly or indirectly.

I've never heard of "criminals" being a protected class in rental applicatians.Race, religion, disability... yes.

Could political beliefs fall under the religion classification?

It's hard enough for a small church to finance much less a conversion, unless it's really a big project.There are some religions that believe that no one should ever enter another church or grounds where other religions were practiced, that's a social stigma that can't be overcome.

done hundreds of deals and hundreds of tenants, only been "attempted" to sue twice and I have successfully sued others twice.. its not common but do expect it, have all of your policies laid out clearly and signed by the responsible parties, follow your rules and policies like religion. 

You don't want them, I'll take their money (and anyone else who qualifies) 24/7-365.Renting (or) not renting based on a persons religion is not allowed in the USA (for a long time--several decades).

As long as you choose not to rent to them via one of these reasons you're fine.Race, Skin color, Religion, Gender, National Origin, Disability, Familial StatusMost of these are pretty straight forward except for the last two.

This is what is on page 1 of the application:Our Criteria:We do not deny housing for race, color, religion, sex, national origin, handicap, sexual orientation, marital status, or familial status.We do deny housing to individuals: when the application is not complete or accurate where there is not sufficient income/resources to pay rent and livewhere there is poor prior tenancy: evictions, violations, damage to rental property, poorly handled move outs, amounts are still owing to landlords or utilities.Criminal activity is at our discretion depending on severity, number of convictions, and how long ago.In your specific case I would deny them for having a prior eviction, unless I could reach the landlord and determine that they complied and have paid amounts owing.