For the IRS guide to religious and charitable organizations, look here:
http://www.irs.gov/pub/irs-pdf/p1828.pdf.
Note that a church is not just taw exempt, it is non-taxableand can only stand to lose rights by filing for 501(c)3 (tax-exempt status). Any contributions given to non-taxable organizations are therefore also tax-exempt, as long as a written receipt is provided by the organization.

For more articles and info, here is a place to start (I have looked at the whole site)
http://hushmoney.org/