Archibald Macleish was not known to have been a religious man. In fact, it was said that he did not believe in the idea of a personal God. 

To discover more about Archibald Macleish's personal beliefs about life, suffering, and death, you may be interested in a 1959 article in Life magazine by three theologians who critiqued Macleish's play J.B. The three theologians are Reinhold Niebuhr, Thurston Davis, and Louis Finkelstein.

All three theologians agree that J.B. (a retelling of the biblical story of Job) raises important questions about man's ability to decipher the reasons for human suffering. In his play, Macleish does not so much question the existence of a merciful God as he does man's deep-seated need to make sense of human suffering. In the play, Macleish rejects the efforts of the three comforters: Zophar (the Catholic priest), Bildad (the Marxist), and Eliphaz (the psychiatrist). 

Finkelstein puts forth the proposition that God alone understands the meaning of human suffering and that this understanding eludes man. He asserts that Macleish accepts this proposition. Meanwhile, Davis theorizes that Macleish's message through J.B. is clear: there is no divine reason for human suffering and certainly no heavenly mechanism at work to intercede on behalf of humankind. 

Source: Three Opinions on J.B. LIFE May 18, 1959