This post is inspired by this bit of news. http://www.10news.com/news/19562217/detail.html
Now, for those who do not know me, I am not exactly a religious person, and actually hold at best apathy, and often antipathy towards organized religion. (Some exceptions for those I respect, like Buddhism.) But this is ridiculous. Misuse of land for bible studies? That set of questions could describe dinner for some families! They meet regularly (every night) and give grace (which is prayer and includes 'amen').
While freedom of religion does not give one the right to do anything one wants, it does mean the government doesn't get to interfere with private religious matters that are otherwise lawful. And having a regular group of friends (even if its 15 friends) over is otherwise a legal event, so having some special law make it illegal just because its religious in nature is offensive, in addition to being unconstitutional.
Now, if one of the couple turned out to be a pastor, or pastor-like figure, and some sort of monies were being collected for charities or something like that, then yes, I could see the argument being made that the house was being used as a church, but even then I'm not sure they should need a license.
So currently, I'm rather hoping the couple wins their case easily and quickly.