(Good Friday special paper edition)
Religious organizations generally want to maximize the number of converts by broadcasting their teachings as widely as possible. Yet, many religions, including the Catholic Church, copyright their theological output. Why would they not want to simply let their teachings diffuse unimpeded? Marchese and Ramello point out that if mediators (e.g., for-profit religious publishing houses) are oligopolistic, then the church can improve its welfare by copyrighting, charging royalties to the for-profit publishers, then plowing that money back into church work recruiting converts in other ways. This effect is particularly large if the church discounts mediated message delivery. That is, copyright by the church is functionally a tax on mediated diffusion of the Word for which the church collects the revenue.
This is an interesting toy model, but I think unconvincing. It is clear that, if the mediator possesses some comparative advantage which allows them to sell what the church otherwise would give away, then when the church budget constraint does not bind, simply paying the mediator a fee to distribute at marginal cost leaves the mediator indifferent and improves the welfare of the church. If the church budget constraint does bind (in extremis, imagine the church only receives revenue through copyright royalty, but that missionaries are 1000 times more effective at converting than church texts), then church copyright effectively functions as a tax on information diffusion used to finance a public good; by the theory of the second best, the distortionary copyright can be a Pareto improvement by correcting another inefficiency related to public good financing.
http://polis.unipmn.it/pubbl/RePEc/uca/ucapdv/marchese160.pdf (The English in this paper is rough, but it is still readable)
A Fine Theorem 