Render unto Caesar what is Caesar’s

“Render unto Caesar what is Caesar’s”? In many European countries, religion comes at a price: If you want the services of a religious community — for marriages, burial, and other activities — you pay a tax.  (In Germany, for example, there is an 8 percent surcharge on your income tax bill.) A very nice Finnish study by Teemu Lyytikäinen and Torsten Santavirta, “The Effect of Church Tax on Church Membership” (Journal of Population Economics, forthcoming), uses this institution to examine the demand curve for religion. 

http://www.freakonomics.com/2012/11/20/the-demand-curve-for-religion/