Machen hired the Dutch Reformed scholar Cornelius Van Til to teach at Westminster Seminary, and defended him against the complaints of the more fundamentalist American Presbyterians. Van Til contributed significantly to the improvement of the Orthodox Presbyterian Church and American Calvinism in general. Among other things, Van Til helped move at least some American Protestants away from their functional deism in civic matters. The Christian faith has implications for the world in which the Church works, and Van Til would not sacrifice a Reformed Christian apologetic to gain mainstream acceptability. For those in the fledgling OPC who wanted to maintain ties with traditional American fundamentalism–characterized by a comfortable public deism, Arminian revisions to the WCF, total abstinence on alcohol–this was a difficult position to accept.
Read more: “Cornelius Van Til and the Identity of the OPC” by Charles Dennison in the OPC’s New Horizons, June 1996.
Also, D.G. Hart and John R. Muether’s “Why Machen Hired Van Til.”
The Machen Seminar 
It’s fascinating thinking about Machen’s relations to Van Til. I think if there was no Machen, no one today would know who Van Til is. Thank you for this post.