Basically, this has to do with income flows and taxation. Individuals pay tax on their income. If someone provides free housing or cleaning for you, you must count that benefit as taxable income. Everyone pays taxes on income. Clergy have had special exemptions. One involves the use of a rectory or parsonage. Under normal rules, it would count as part of your overall taxable income. Clergy were exempted from this general rule. It was never fair. Those of us who were not of their religion were subsidizing them. My tax prof was furious. It should be a violation of the Establishment Clause. There was Supreme Court case law that upheld the exemption. There are many such items in the tax code. I was angered to hear about the exemption. It is so against separation of church and state. Atheists could not claim any exemptions.
Evidently, the time was ripe to raise the issue again. To be honest, though, the present Court finds religion and state should accomodate each other frequently. The cases have been 5-4, though. Republican nominationees vs. Democratic nominees. One must have an actual case in the United States to challenge legislation or the constitutionality of a an act. This appears to be the opening move. Freedom from Religion sued. A trial court judge has ruled that the Tax Code provision is unconst'l. Next, the case will be heard by the intermediate level appeals court, the Court of Appeals for that geographic area. There is a good chance that the case will be heard before the U.S. Supreme Court. I have no idea how one can justify the exemption. It clearly benefits a religion.
I will try to read the trial court's opinion. This is great news. Freedom from Religion has a good track record of winning these cases. I honestly don't know much else about Freedom from Religion. If you research Establishment Clause law, they bring cases routinely and from all over the country. I don't know why the ACLU is not more prominent in this field. Perhaps b/c Freedom from Foundation does such a good job that it frees the ACLU's resources for other civil liberties causes. The embarassing part is that the exemption has existed for so long.