The way this works is that you start your church, and you have people tithe 20% of their income to it (obviously you have to have everything set up in a way that generates explicit trust) We'll just use flat 100's because it's easy even if percentages are evil.
(Also this works better if you're all younger and more single but REVOLUTION IS POSSIBLE AT ANY TIME)
Typically you're locked into not being able to do anything more than 43% of your household income to purchase a property. BUT! With 10 people contributing 20%, you now have twice the available income available to your church!
This means you can have up to 86% of your collected household income as your mortgage expense! To fulfill your church goals of providing effective housing to people!
This also means you can have the church pay off the 4plex faster!
And then, the 4plex is now generating revenue, and you can either reduce the amount you tithe to the effort, or increase your purchase capacity.
Because your costs no longer include a mortgage, you can rent for repair/maintenance tax costs, which is SIGNIFICANTLY BELOW MARKET RATE.
ANYWAY.
Hopefully this makes sense, I'm happy to answer any questions you might have about any of this. Start a church! It's like a corporation but you can do spooky stuff with it!