While membership in mainline Protestant churches in the US has been on the decline for decades, church leaders are sounding the alarm more loudly after a recent study offered a grim picture of the churches' future.

"There is no future for The United Methodist Church in the United States unless we can reach more people, younger people and more diverse people," said the Rev Lovett Weems, a researcher and professor of church leadership at Wesley Theological Seminary in Washington, according to the United Methodist News Service.

Weems made his comment after viewing findings from the Pew Forum on Religion & Public Life survey, which was released last week. The study showed nearly half of American adults said they left the faith tradition of their upbringing and either switched religious affiliations or left the faith tradition altogether.

Of the 53 per cent who left the Methodist Church of their childhood, 19 per cent went to evangelical churches, 11 per cent to other mainline Protestant churches 3 per cent to historically black churches, and 8 per cent to a non-Protestant religion. Moreover, 12 per cent say they no longer are part of any faith group.

Although the Pew study confirms previous data collected on The United Methodist Church and religion in the United States, many say the study provides a comprehensive and more detailed picture of the latest trends in the US religious landscape.

Of the 78 per cent in the country who are Christian, according to the Pew survey, 18.1 per cent belong to mainline Protestant churches - which are predominantly white and elderly - and of that, 5.1 per cent are United Methodist.

"For whatever reason, a sizable population raised in the Methodist tradition is no longer Methodist. Maybe we haven't done a good job of showing what is unique and special and important about being a United Methodist," said Scott Brewer, director of research for the United Methodist General Council on Finance and Administration, which collects statistics for the denomination, according to UMNS.

United Methodists in the United States have been decreasing steadily in number for at least four decades and the denomination is currently at around 8 million members.

But the loss of members has not come without outreach efforts.

"It's not that we're not making the efforts or spending the money to reach younger and more diverse people, but we're not focusing our efforts on outcomes," said Weems.

The United Methodist Church, which is still the third largest church body in the country, has spent millions of dollars on its "open hearts, open minds, open doors" media campaign.

Television, radio and cinema spots, billboard ads, and now internet ads have been running for nearly eight years to communicate the key characteristics of the denomination to the American public. A survey found that the campaign is helping reframe people's perceptions about the Church into something more positive, according to the Rev Larry Hollon, chief executive of United Methodist Communications.

His view is backed up by the survey's other findings, with 54 per cent expressing a willingness to visit a United Methodist church, up from 47 per cent in 2006.

Still, the US has become a "vibrant marketplace where individuals pick and choose religions that meet their needs", according to the Pew survey. And denominations are no longer a major factor for people when selecting a church.

"A lot of people say denominations and traditions don't matter any more, but I don't think that's the case," said Weems, as reported by UMNS. "I think it's just no longer the deciding point and often not the beginning point when people select a church."

Acknowledging the changes in religious affiliations and attitudes toward religion in the US, the Rev Jerry D Campbell, president of United Methodist-related Claremont School of Theology in California, says churches have got to get comfortable with change.

He hopes the Methodist tradition continues to be a part of the religious landscape in America.

"God apparently doesn't like static environments," he said, according to UMNS. "I think we have to realise that the fate of God's future for humanity is not limited to the success of the institutional church. Even if the church dies, God doesn't die."