Barber began work on the piece in 1942 and, after several interruptions, completed it in 1954, when it was premiered. He chose a selection of prayers by philosopher and theologian Søren Kierkegaard. He is, of course, the Danish philosopher and theologian whose work continues to be tremendously influential, and particularly do during that mid-twentieth century time. Barber selected prayers for his books and journals. As quoted on this site, "One finds here three basic truths: imagination, dialectic, and religious melancholy. The truth Søren Kierkegaard sought after was a truth which was a truth for me."
I found a video of one of the sections: https://www.youtube.com/watch?v=pWV4t_axC58 My recording at home is conducted by the renowned Robert Shaw on the Telarc label, along with Bartok's Cantata profana and Vaughan Williams' Dona nobis pacem.