Homeless shelters would be a good start

Brothels. Bars. Gaming. No seriously, schools, convert them to apartments for low income. Shelters for battered women/kids. Course if religion died out might there be less violence?

Lecture halls; schools

Bullshit Museums.

Afraid that is a bit of wishful thinking that isn't going to happen in our lifetimes. Once the bank 'repossesses' them, it would be up to the bank...

Pretty sure based on what I know about churches I'm pretty sure they'd start selling condos and discriminate against their constituents.

Most of the smaller ones have pretty good acoustics, so event venues comes to mind; as does shelters and soup kitchens.

Homeless shelters, Rehabilitation center

Make them libraries or educational institutions.

Homeless shelters. food kitchens, free healthcare clinics,... All funded by church donations.

Concert venues! Especially the older churches.

Churches were designed for high social meetings and events, anything to that effect will do well.

They make also high end apartments or homes. Not so great for the homeless or poor because of often high ceilings, exposed Windows . Poor insulation and high cost of energy. Many churches already are for sale cheap. I can build a new building and home many times cheaper and healthier.

This is a little off subject, yet I'll add this anyway. There is a show that aired on the History Channel some years back about "Dixie", ie. the southeastern states. One fact that stuck with me is there are more churches per capita in Dixie than in any other region of the US! I thought of converting the old churches to theaters for plays.

Burn them to the ground. Never leave 1 cancer cell around. Build something new

I am a boomer. When the boomers were school age, schools were built. When the baby bust followed, school districts sold schools. The elementary school my former husband went to was bought by a church. Real estate never lies around, it will be bought and re purposed. There is no lack of demand for space. They might lose some money but I don't see that as being a concern.

Homeless shelters, soup kitchens and youth centers come to my mind.

Having both done, and attended numerous concerts in various church buildings - I'd say they make dandy concert halls. Especially the old ones with cathedral ceilings !

Or meeting houses, or dance halls !

I also knew a couple that bought a small old church, and made it their home. They put their bedroom up on the alter. Brilliant !

The church I was taken to when I was young , got turned into an apartment complex . I now actually live in the same neighborhood now . My dad's parents lived "directly" across from it .

Whoever purchases the land would decide. It sure would be something to see churches change into places of business, community outreach, private homes, shelters, schools... the sky is the limit.

Bars. Strip clubs. Haunted attractions. Casinos.

I've always had a fantasy about converting abandoned churches into schools and libraries. I'm thinking libraries for the fancy stone ones and schools for the more ordinary house-looking ones.

charities

Community space for education (not just primary learning, but life skills and hobbies/crafting/making), crèches, homeless/food centers, libraries, meeting space, lectures, events.

Music venues, art studios, Homeless shelters, community centers,

Already happening .. homes, offices, performing arts, shops