Take two hypothetical people. And when I say "people," what I really mean is "taxpayers." Let's call these folks "Attorney Alice" and "Minister Mike."
Attorney Alice works for the law firm of Nasty, Poor, Brutish & Short LLP, which pays her $105,000 a year in salary and structured bonuses.
Minister Mike works for Innocuously Bland Protestant Ministries of Springfield, which pays him $105,000 a year, in the form of a $40,000 annual salary and a $65,000 annual "housing allowance."
Neither of these hypothetical characters receive any additional benefits like contributions to retirement accounts or health insurance; both are the sole breadwinners for families of four; both are homeowners; and the above exhaustively describes the money coming in to both of their households.
What's the result? Attorney Alice pays $24,576 in state and federal income taxes. Minister Mike, who you will recall brings home the exact same amount of money, pays only $1,540 in federal and state income taxes -- one-sixteenth of Attorney Alice's tax burden.* Read all about it from the tax preparer's perspective. (Via.)
I'm sure you can guess which one of the two asked for a discount on the tax preparer's fee.
You don't need to be an atheist to see that this result is unfair. It might help to be a lawyer or an accountant, though, to see a Constitutional problem. See, in law school, I was taught that the tax code is written the way it is so that the government can encourage certain behaviors and discourage other behaviors. This example illustrates a powerful incentive for people to pursue careers in religious ministries. That, in turn, would seem to represent a clear preference by the government for religion over non-religion, which when expressed thusly rather clearly violates the Establishment Clause. (See, e.g., Board of Education of Kiryas Joel Village School District v. Grumet (1994) 512 U.S. 687, particularly the phrase "...a principle at the heart of the Establishment Clause, that government should not prefer one religion to another, or religion to irreligion.")
Now, I don't really have a problem with the government choosing to say that the ministry is a public service profession. I'd readily agree that most ministers, in most settings, provide a variety of benefits for their communities. That they could do so in a secular fashion is irrelevant; they can do so in a religious context and they may express their professional activities as being part of a set piece inseparable from their faith and theological beliefs if they so desire. I don't get to choose your religious ideas for you and if your faith gets you to behave in a noble, morally good fashion that benefits your community, I've no cause to object.
What I want, though, is equality before the law. I, too, am engaged in a public service profession; I assist people with their social problems; I guide them through tough times, I hold their hands while they cry, and I give them advice to help resolve disputes. I am significantly more accountable to the public and significantly more regulated by the public in the practice of my profession than the minister is in his; I am thus even more burdened in the practice of my profession than the minister, all other things being equal (the key equality here being gross income).
So if a minister gets to knock more than half his income out above the line and double-deduct things like mortgage interest, property taxes, and homeowners' insurance, then I should be able to do that, too. It's not fair that because I base my guidance in dispensing that advice from books of law, and the minister bases his guidance on an ancient holy book, the government should treat him better than it treats me when it comes time for us to pay our taxes.
Maybe I should call myself a "minister of judicial dispute resolution" instead of "attorney."
And while I'm on the subject of Establishment Clause violations, I just have to recognize and give thanks to Dan at Bleakonomy for a very amusing shout-out. Merry Christmas, dude.
* To be fair, Minister Mike in this example opted out of Social Security and Medicare taxes, and therefore will not be entitled to participate in those benefit programs upon his reaching retirement. Attorney Alice is legally required to participate in Social Security and Medicare.