WASHINGTON — President Trump signed his long-awaited executive order on religious liberty Thursday with a full-throated reassurance that he would protect the freedom of American believers. But the reactions of religious leaders across the country suggested that it instead promised freedoms many of them did not want — and failed to deliver concrete legal protections that conservatives had been led to expect.

The centerpiece of the order is a pledge to allow clergy members and houses of worship to endorse political candidates from the pulpit, fulfilling a campaign promise that Mr. Trump repeatedly used to rally his most fervent supporters. Public opinion polls show, however, that neither the American public as a whole nor religious leaders in particular — even evangelicals, who voted for Mr. Trump in droves — think that partisan politicking by churches is a good idea.

“I don’t actually know anybody who has endorsed or who wants to endorse a politician from the pulpit,” said Leith Anderson, president of the National Association of Evangelicals, an umbrella group representing about 40 denominations and 45,000 churches. “My idea is that church is about teaching the Bible, it’s about discipleship and evangelism. It’s not about politics.”

The order was also a stinging disappointment for conservative religious leaders who had expected that it would exempt their organizations from Obama-era regulations aimed at protecting gay people from discrimination.