I don't agree. There are hundreds of churches throughout the land whose national churches have been infiltrated by the left who have been successful in making denominational changes. But the individual churches have rejected the changes and remain faithful to the faith passed down through the ages.
Technically, the building belongs to the national church, but it was build, maintained over the years by the faithful. They have married, baptized, confirmed and buried their family there sometimes for generations. They are not going to turn over their church to an unseen bureaucratic church, nor should they. They just do their best, in His Holy Name.
True, however the REASON mainline denominations continue to be controled by non-believers is because of the ENABLING that otherwise biblically faithful congregations provide, in paying their required dues.
If the individual churches which are biblically faithful....REFUSED TO GO ALONG WITH SUPPORTING the apostastate denominational leadership, the mainlines couldn't operate. Instead, people remain "nice" and get along to go along, ignoring the fact that the mainline Lutheran, Presbyterian, Episcopalian, Churches of Christ, etc., ALL, are on record strongly supporting abortion, euthanasia, homosexual clergy, sexual immorality, communist regimes, and ignoring the authority of the Bible.
If you stay in an organization which is anti-biblical, and anti-Christian--even if you don't directly participate in it's apostasy--none-the-less you are lending support to that apostasy--just because you're there.
Biblically faithful believers who remain in those mainline denominations are like genuinely conservative "Democrats" who hate everything the Democrat party now stands for...but remain Democrats, supporting Democrat candidates they despise.....just because, well, they and their family have always been Democrats.