(Image: SBC website)

The biggest U.S. Protestant group is preparing to meet in Columbus, Ohio but it has reported its largest annual decline in more than 130 years - a loss of 236,467 members.

With just under 15.5 million members, the Southern Baptist Convention remains the largest Protestant group in the United States. But it has lost about 800,000 members since 2003, when membership peaked at about 16.3 million, Christianity Today reported.

The number of SBC baptisms has declined in eight of the past 10 years, according to the denomination, The Associated Press reported. In 2014, baptisms declined by more than 5,000 to just over 305,000.

This past year, however, the number of SBC churches grew by 1 percent to 46,449, Christianity Today reported.

That's in part due to church planting efforts, aimed at starting new churches. Southern Baptists started 985 new churches in 2014, up 5 percent from the previous year.

Yet a new major survey from the Pew Research Center shows a similar decline for the SBC. In 2007, Pew found that about 6.7 percent of Americans claimed to be Southern Baptists. In 2014, 5.3 percent of Americans were Southern Baptists.

Pew also found Southern Baptists are aging, with the median age rising from 49 in 2007 to 54 in 2014. That makes them older than Nazarenes, "nones," and non-denominational Christians, but younger than Presbyterians, Episcopalians, and Methodists.

Frank S. Page, president of the SBC's Nashville-based executive committee, said that the numbers were disappointing.

"The truth is, we have less people in our churches who are giving less money because we are winning less people to Christ, and we are not training them in the spiritual disciplines of our Lord," he told Baptist Press.

Mark Woods wrote in the UK publication Christian Today, "With all due respect to Thom Rainer and Frank Page, it doesn't seem likely that the decline is down to a lack of prayer or effort.

"It may be something rather more fundamental: that the SBC label is associated with a kind of Christianity which is not attractive in the kind of country America is becoming, which is far more socially liberal than many evangelicals are comfortable with."

Ina piece headlined, Is the Southern Baptist Convention in terminal decline? Woods wrote, "The SBC still has a lot going for it, and while it might be argued that a softening of its line in certain areas would make evangelistic sense, it is likely to remain a power in the land for years to come."