New members trying to install the desktop application during the past week or so were not able to because our developer code signing certificate had expired, but that's resolved now in the updated version. This issue also affected anyone who uninstalled and tried to reinstall. Anyway it's all fixed now, I think.
So if you had trouble installing, try again now. Latest version always available at:
https://christianchat.com/mac/
Please note, when I tested this latest installer on a Mac, for some reason it showed some warning message and prompted for some special password, but I simply ignored the password request and clicked "Always allow" and it installed and worked with no problem.