Someone pointed out the other day that an estimated $71 billion per year is lost in US tax revenue because of religious tax exemptions.
If religious organizations paid taxes like everyone else, NASA could send 28 rovers to Mars per year...EVERY YEAR. FOREVER.
(Total Cost of current Curiosity mission : $2.5 billion, including $1.8 billlion for spacecraft development and science investigations and additional amounts for launch and operations. )
Perhaps we should be asking questions that have to do with why we place such little importance on advancing our knowledge and more on preserving arbitrary religious orders.
While I'm not a religious person, and you won't be seeing me give money to any church, it's not that simple. Firstly, the idea that you can calculate the loss in taxes by just applying the tax on paper is fundamentally incorrect, since the tax itself creates an incentive not to spend money that way.
Secondly, churches spend part of the money on social assistance, and so a reduction in their income may increase the funding needs for governmental assistance programs.
I'm not fundamentally opposed to cutting tax breaks for churches, but living in a country where recent tax increases have lead to a massive tax revenue reduction, I felt the need to point out that you probably couldn't fund 28 rovers with it.
"churches spend part of the money on social assistance"
As a vehicle for proselytizing. Organizations that are dedicated to social assistance have reporting requirements that churches don't. It's not transparent at all what churches spend their money on. It's a murky government-sponsored wealth redistribution scheme. Not unlike the financial industry in that regard.