There is precious little free Bible study software out there for Mac but Bible Desktop is an attempt at providing something that normally can go for anything up to a few hundred dollars.
Bible Desktop runs across platforms and like MacSword, relies on the JSword project to for content so you're guaranteed a huge amount of free content from Commentaries, Dictionaries and Daily Devotionals to more General Books and Hymns. However, the problem is accessing these books. On installation, you're asked if you want to install a Bible or test from the JSword project.
Bible Desktop proceeds to warn you that you are accessing the internet to download the books but nothing happens. You can try again manually by going to "Tools" and the "Books" but the same thing happens again. In the Help section, the developers warn that "if you live in a country which monitors internet activity, you may want to find another way to obtain Sword modules". I can't be sure the problem had anything to do with this but most annoyingly, it fails to specify what these alternative methods are effectively rendering the program useless to me.
Bible Desktop looks like a basic if noble attempt at providing a free Bible study program for Mac. However, I hope you have more luck than me trying to download a Bible or passage to load into it otherwise it's not much use at all.