On August 30, 1979, the Board of Trustees of the Presbyterian Guardian voted to merge the magazine with the Presbyterian Journal.
Frustrated with a subscription base of about 3,500, the Trustees joined with the Presbyterian Journal in order to "reach a wider audience (well over 20,000) with the Reformed faith." In his article, "Toward the Future of the Presbyterian Church" in the Guardian's final issue, Edmund Clowney wrote, "there is no good reason for [the two magazines] to remain separate, and every good reason why there should be one clear journalistic voice serving Machen's hope for American Presbyterianism." For many, the merger was a precursor of a denominational union that was perceived on the horizon. In Clowney's words, the merger "marks the growing unity of Bible-believing Presbyterians in the United States." The anticipated church union, however, would not take place. The Presbyterian Journal, even with a united voice and expanded subscription base, would cease publication in 1987, with its Board of Trustees transferring its assets to World magazine.
The 1979 merger ended the remarkable 44-year life of a magazine founded by J. Gresham Machen in 1935, an independent monthly dedicated to a predominantly Orthodox Presbyterian readership. Numbered among its editors were Ned B. Stonehouse, Paul Woolley, Leslie Sloat, Robert Nicholas, and John Mitchell.