When he visited Colorado for the first time in 1879 he met the widow of John Wesley Iliff, Mrs. Elizabeth Iliff. They were married on December 27, 1883. He was a co-founder of the Iliff School of Theology in Denver, Colo..

He was editor of The Study and published:

On May 5, 1912, Bishop Warren retired from the Iliff School of Theology. On July 23, 1912, he died of pneumonia at his home in the University Park neighborhood of Denver. He was buried at Fairmont Cemetery in Denver.

This article incorporates text from an edition of the New International Encyclopedia that is in the public domain.