According To Islam Sharing Islamic Content is a great work.There are some people who earn money just by sharing Islamic content though they are not the owner of the content. As the same time, the Islamic content they are sharing isn't copyrighted. Is it halal to earn money in this way?
All perfect praise be to Allah
There was no concept of copy rights back in those days(i am considering all islamic content in this, including quran, books of ahadees etc). And it is not practice of islamic scholars to have copy rights. That content was is usually meant for benefit of everyone, not for some earning purposes like for writing novels etc. But this does not mean that any one can share that content with their name. One can not use his name on them, because its a lie, and morally wrong.
If i try to answer only the part of your question, which is that is earning from islamic content, or teachings is permissible or not. Than answer is yes, it is permissible(please consider that there are some scholars, who forbid earning from Quran specifically, but their view is weak) and some earning of this kind was shared by Prophet Muhammad peace be upon him too.
And their is a saying of prophet(PBUH)
“The thing for which you most deserve to take payment is the Book of Allaah,” (narrated by al-Bukhaari)