Politics has become a religion and a source of identity to evangelicals, Russell Moore lamented over the weekend, as he warned that the witness of evangelicalism was at risk.

Moore said that evangelicals become more caught up in over-promising at each election cycle than the rest of American culture. Speaking at the Southern Baptist Church's ethics and religious liberty commission's national conference, he said evangelicals' obsession with politics had led to Christians becoming either disillusioned or cynical.

"There are no final victories or final defeats" in election cycles, Moore told the conference on Saturday. He said he had heard people say "this is the most important election we have faced in my lifetime," during every election cycle, and been told the election will either win or lose the country completely.

"We have a responsibility not only to speak truthfully. But we have a responsibility to contextualise not only to the present culture but to the future," he said. "We have to speak in words that we can live with for future generations of evangelical Christians and our neighbours. And as we're doing that, ensuring the fact that the gospel is clear."

He added he was concerned about "what happens to the witness of evangelicalism in the middle of the moment like this".

Moore warned that politics had become a form of religion with people finding their primary source of identity in who is with them or opposed to them politically.

When that happens it is easy for the gospel "to be a tool to accommodate whatever political agenda is useful at the moment," Moore added.

"Part of what we have to do is to dethrone politics as a religion and as a source of identity while at the same time remaining engaged in our responsibilities as citizens, in communities and neighbours, which includes the political process."

Moore, who has been an out-spoken critic of Trump and his supporters, also said some evangelical leaders risked damaging the gospel's witness in years to come.

"Evangelicals, who have previously said character matters, who this year are saying character doesn't matter that much, are never going to be able to address the issue of character again. Never," he said.

"For me the primary issue is not who's up and who's down in the horse race in 2016. It's what is the gospel witness of the evangelical church going to be in 2017 and 2018 and 2028 when you have this variety of problems."

He went on: "What do we do to rebuild after this debacle? Long term though, it could be that this nightmare of an election season is pressing some issues to the forefront and exposing some very real differences in terms of Christian witness and otherwise in this country that can productively lead us toward the future."