The problem with some of Machen's children is not that they are warriors. To accuse them of that would actually be to flatter them somewhat. Rather, it is that they have lost sight of Machen's (and Paul's, and, indeed, the Bible's) deepest concern, which was always the gospel and which concern was crystal clear in his life, his writings and his preaching.
From another part of his post:
When we identify the church with the gospel, it would seem to me that Rome is the natural outcome, since, for Rome, the church is, in effect, the gospel.
Talk of ecclesiology and Two Kingdoms has its place. But if Paul's emphases are to be respected, both are to be kept strictly subordinate, structurally and emphatically, to the gospel, the good news of what God has accomplished in Jesus Christ. My concern is that, when ecclesiology and 2K are all some people ever seem to talk about, the gospel is eclipsed or - even worse -- ecclesiology and 2K ideology become not adjuncts to and inferences of the gospel, but the very gospel itself.
You can read the rest here. It has something to offend just about everybody in Reformed circles, but the main point is something we all need to hear.