Let's face it. Unix isn't for everyone. Here are some reasons you might not want to take the plunge.
Face it: you're busy, especially if you're active in the public ministry! You don't have a lot of time to spend learning a new operating system. Unix isn't Windows, either. You'll have to spend some time, maybe a lot of time, learning to configure and use your Unix system.
On the other hand, that might be just what you need. As a theologian you've probably done a lot of learning and study already. I found a lot of relaxation and enjoyment studying Unix in my (infrequent) spare moments. Unix just may be the relaxing pastime you've been seeking!
I haven't found many either. Most applications are written for Windows, period. Theological applications aren't easy to find.
Take stock. What do you need? The only specifically theological application I ever used on my PC was Quickverse for DOS. It ran very well in DOSEmu under Linux.
However, you might use more than that! The main applications I see missing for Unix are church membership packages and electronic libraries. If you need these but still want to run Unix, all is not lost. Packages like DOSEmu and VMware, even Wine make it possible to use your DOS/Windows applications under Unix. My guess is that more and more theological applications will become available as Unix becomes more popular on the desktop. Keep an eye on the Theological Applications Page for updates!
Maybe you just don't have the desire to move to a different operating system and applications. There's no sin in that! If you should ever become dissatisfied with your current system, however, remember that you have other choices.