Why are Christian books not Public Domain? In Matthew 10:8, disciples were told to even freely heal people, since it was freely given.

Paul, in order to not be a burden to others, made tents to support himself.

Given this, why are most Christian books written today copyrighted, rather than in the public domain? [Yes, I know that some are freely available online; but most are not.]

One might ask: how would having such works in the public domain be useful to Christianity? For one, it would be useful to build a gigantic index, sorted by topic, where for each topic, one could look up all the well known Christian authors and read segments of their books related to the topic.

Back to the original question: why are most Christian books not public domain?
The reason why Christian books (and music) are valid objects to have copyright protection is simply because the great deal of effort in making them and in some cases a livelihood based on them.


  For it is written in the Law of Moses: “Do not muzzle an ox while it is treading out the grain.” Is it about oxen that God is concerned? Surely he says this for us, doesn’t he? Yes, this was written for us, because whoever plows and threshes should be able to do so in the hope of sharing in the harvest. (NIV 1 Corinthians 9:9-10)


A book is just a sermon in print so the laborer deserves wages for his work.  Having said this any good part of these works is God in them and not properly objects of copyright, but the copyright is for the effort of the person in the work regardless of quality. Additionally publishers make available old works providing new translations in modern language and other enhancements which qualify as a service worth payment.  

Very good books will eventually be read long after their copyright expires, so in a sense God does provide them all free.  The best ones actually are free.