In his essay Haykin has a footnote with two quotations from Machen that clarify where be stood on the matter of fundamentalism.
The term fundamentalism is distasteful to the present writer and to many persons who hold views similar to his. It seems to suggest that we are adherents of some strange new sect, whereas in point of fact we are conscious simply of maintaining the historic Christian faith and of moving in the great central current of Christian life.
Thoroughly consistent Christianity, to my mind, is found only in the Reformed or Calvinistic Faith; and consistent Christianity, I think, is the Christianity easiest to defend. Hence I never call myself a "Fundamentalist." There is, indeed, no inherent objection to the term; and if the disjunction is between "Fundamentalism" and "Modernism," then I am willing to call myself a Fundamentalist of the most pronounced type. But after all, what I prefer to call myself is not a "Fundamentalist" but a "Calvinist"- that is, an adherent of the Reformed Faith. As such I regard myself as standing in the great central current of the Church's life - the current which flows down from the Word of God through Augustine and Calvin, and which has found noteworthy expression in America in the great tradition represented by Charles Hodge and Benjamin Breckenridge Warfield and the other representatives of the "Princeton School."
Both quotations are from Stonehouse's Memoir,.