At a talk on aging at Community United Church of Christ recently, the host prefaced her introduction by saying that the event was not political and that the discussion would pertain solely to the issues.

The comment was not just throat-clearing. Members of the Raleigh congregation are especially skittish these days about mixing church and state concerns since it was disclosed that the Internal Revenue Service is investigating their denomination. At issue is a speech presidential candidate Sen. Barack Obama gave to 10,000 people at a church conference in Hartford, Conn.

The IRS wants to know whether UCC jeopardized its tax-exempt status by having Obama speak to its members in June. The IRS tax code prohibits churches and other tax-exempt institutions from participating or intervening in a political campaign on behalf of a candidate.

The investigation has caused a trickledown of unease, so that speakers at local churches are warned about being "political."

"There's probably a heightened sensitivity that churches need to be careful in how they handle the exuberance of this political season," said Stephen Camp, the conference minister for the 225 United Church of Christ congregations in North Carolina and Eastern Virginia.

Camp sent a letter to all members of the Southern Conference explaining that the 1.2 million-member denomination invited Obama before he was a presidential candidate. The Illinois senator, a 20-year member of Trinity United Church of Christ in Chicago, was asked to address the intersection of public service and personal faith.

Since news of the IRS investigation was made public last month, local churches have tried to keep members up to date. The Rev. Richard Edens said he understood that some people were alarmed by the probe, but he felt confident that the denomination would convince the IRS it had done nothing wrong. Edens' congregation, United Church of Chapel Hill, is committed to the separation of church and state.

"We don't think churches should endorse campaigns," Edens said.

He pointed out that no buttons, banners, pins or other campaign paraphernalia were allowed in the Hartford Civic Center during Obama's speech to prevent the appearance of a campaign rally. But about 40 Obama volunteers promoted the campaign on the sidewalk outside the civic center.

"We're always careful," added the Rev. Jill Edens, the co-pastor. "It's not out of fear, but out of sensitivity to people of different persuasions."