One of the leading Reformed Christian scholar responding to the Insider Movement is David Garner, a professor from the Westminster Theological Seminary (WTS).
He was the chairman for the three year study committee on the Insider Movement for his denomination, the Presbyterian Church of America (PCA).
He has written a five part series over at his blog with the Alliance of Confessing Evangelicals that must not be missed. It took him several months but he completed at the end of last month!
The following are the links to his articles:
The Domain for Truth 