At the very least, Du Bois was an agnostic. He was also influenced by German thought. His negative attitude towards religion was registered for example in his Autobiography, published late in life. Here is an extract:
W. E. B. Du Bois on Religion
However, Du Bois did express himself in edifying language with a quasi-religious valence. Case in point, this poem inspired by the Universal Races Congress of 1911:
"A Hymn to the Peoples" by W. E. B. Du Bois
Note the peculiarities in Du Bois' use of religious language. Two questions immediately come to mind:
(1) What is meant by "God" in this poem?
(2) Does "World-Spirit" refer to Hegel's notion?