By "Christian" I don't mean whether or not they expounded Christian virtues, but to what extent did they align with mainstream Christianity? Were the Taiping armies made up entirely of Christians or were the majority of the people loyal to the Heavenly Kingdom followers of Confucianism/Chinese traditional religion?
In "From Yao to Mao," professor Kenneth Hammond explores the background of Xiquan.
Xiquan never read a bible until after his conversion. his first contact was with Jesuit missionaries while he was studying for the Imperial examinations during which time he acquired some Jesuit literature - described as "pamphlets" by Hammond.
After a string of failures, Xiquan - while in self-imposed and possibly depressive seclusion - first had his visions and began his association with Christianity.
Hammond does not elaborate on the belief system, but indicates that it put more focus on political decree than theology.
The lack of formal training and political nature of the God-Worshipping Society suggests a system of belief that has less in common than more.