After the breakdown by Roberts, he stayed with the Penn-Lewises from 1905. He and Penn-Lewis co-wrote "War on the Saints" (1912). The book continued the controversy over whether demons were influencing Revival-associated beliefs. The writers described their book as "a testimony against the outbreak of demons upon the spiritual Church, which followed the outpouring of the Spirit of God in Wales." Both writers blamed Satan for the activities in the unconscious mind, and both writers believed that Christian believers could fall victim to spirit possession. There was a theological dispute about the validity of either idea.