The Pew Forum has provided this helpful resource for churches to know what political activities are permitted under IRS non-profit restrictions.
You can find this and other helpful resources at AdvanceUSA’s Church Involvement Page. Pastors and churches are often too intimidated speak out on important political issues for fear of losing tax-exempt status. Christians have a responsibility to act as “salt and light” in our society and culture, and must be armed with accurate information about what the law allows.