General
What constitutes a Church under federal tax law
Churches, taxes, and the Constitution (very much background reading, as the article is from 1969, but it is useful)
Pro — Websites
Pro
You give religions more than 82.5 billion per year
How to make $71 billion/year: Tax the churches
Top 10 reasons churches should not be tax exempt
Churches are parasites on the tax payer
Con
Should Uncle Sam tax churches?
Why churches are tax exempt in America