Via CT:
Mainline Protestants (those in the United Methodist Church, Evangelical Lutheran Church in America [ELCA], Episcopal Church, Presbyterian Church [U.S.A.], American Baptist Churches, United Church of Christ [UCC], and The Christian Church [Disciples of Christ]) have fared poorly in recent decades. While Christianity overall is not dying in America, Mainline Protestantism is getting closer. According to the GSS, 28% of Americans identified with a mainline church in 1972. By 2014, that number had dropped to 12.2%.
A recent report from the Presbyterian Church (U.S.A.) corroborates this trend. The report looked at church statistics from 2002 to 2013. The denomination reported net membership losses each year. In 2002, the denomination shrank by 41,812 members. This number peaked in 2012 when they reported a net loss of 102,791.
Other Mainline denominations faced similar declines due to several factors, including aging membership, falling birthrates, a lack of theological clarity, and a shortage of new churches. Mainline Protestantism as a whole is hemorrhaging and is facing an existential crisis. If the current trajectory continues, some Mainline denominations could cease to exist in the next four to five decades.