Jacob A. Loewen, former Mennonite Brethren missionary in Columbia, professor at Tabor College 1958–1965, and later Bible translation consultant with the Unite Bible Societies in South America and Africa, and Wesley J. Prieb, lifelong professor of English at Tabor College, co-authored this volume as a very personal testimony to the Mennonite Brethren Church and as an appeal to the larger Anabaptist/Mennonite world.

Only the Sword of the Spirit reconstructs the developments of Menno Simons's Anabaptist Vision and methodically traces its evolution through the entire northern stream of Mennonites─Holland, Prussia, North Germany, Russia, and North America. It highlights some testimonies of fidelity and some embarrassing accounts of slippage in the almost 500 year pilgrimage of these Mennonite peoples. It concludes with an appeal for the recovery of a relevant version of Menno Simons's sixteenth-century vision for our own times.

According to the authors, "an underlying thesis of this book is that by emphasizing nonresistance during war as a single agenda and test of fidelity, Mennonites have often closed other doors. It is as if we want Jesus to enter our peace room during wartime, but not when it concerns everyday issues of peace and peacemaking. And what about other rooms, our financial room or stewardship room? Unless all the rooms are occupied by the Lord of the House, even the peace room will eventually be closed. Jesus knocks at all our doors (Rev 3:20–22)" (from the Introduction, xi).