Boyle, Samuel E. The Christian Nation: A historical and biblical study of the Reformed Presbyterian (Covenanter) concept of the mediatorial kingship of the Lord Jesus Christ over nations (1638-1968). Pittsburgh: Christian Government Movement, 1971. 
Staple-bound, printed gold wrappers, 10 chapters with each numbered separately, about 150 pp. 8 1/2 x 11. Good.
Samuel E. Boyle (1905-2002), b. in Kansas, Reformed Presbyterian missionary to China beginning 1934, founded the Reformation Translation Fellowship in 1948.
Written as a research project "to try to understand the historical origins and the Biblical principles which have let to the current effort to secure a Christian amendment to the Constitution of the United States."