A Repeat of History in the Church of Scotland

Writing of the origin of the Relief Church, one of the early secessions from the national church in Scotland, William Blair comments:

“From the terms employed by Thomas Boston (junior) in December 1759 when he demitted his charge we learn how the evangelical party in the Church of Scotland was waning and the moderate party gaining strength:

"Those who adhere to the ancient principles and practice of the Church of Scotland are now reduced to such a small and inconsiderable handful, that they are quite run down by their numerous opponents, and have it not in their power to reform those crying abuses, nor to do justice to the oppressed, while they continue in the communion of the Church."

(“The United Presbyterian Church; a Handbook of its History and Principles”, William Blair, 1888)

Boston followed the logic of his argument; he left the national church in order to exercise a gospel ministry in an evangelical Presbyterian body, uncompromised by the spiritual indiscipline of the national church.  It might be argued that Boston was wrong and the evangelical cause (perhaps in response to the strength of the various secession churches) did indeed grow in the national church after 1759.  However, that growth was so resisted by the liberal wing that the majority of these evangelicals themselves left in the Disruption of 1843 and joined the Free Church of Scotland.

When it becomes impossible to reform crying abuses and exercise biblical discipline, is it right to continue in the communion of that denomination?