Final answer:
The Oklahoma Socialists openly used the beliefs of fundamentalist Christianity to argue that socialism was more moral than capitalism, reflecting the trend of some socialists reconciling religious ethics with their social and economic philosophies.
Step-by-step explanation:
The views of Oklahoma Socialists on Christianity can be understood within the broader context of Socialist perspectives on religion during the early 20th century. While socialists like Karl Marx viewed religion as inseparable from the economy and society's inequalities, this did not necessarily translate into a rejection of all religion by socialist parties or movements. Indeed, many socialists understood the value of moral arguments grounded in religious belief when critiquing the excesses of capitalism.
Looking specifically at the answer choices provided, it's most accurate to say that Oklahoma Socialists (C) openly used the beliefs of fundamentalist Christianity to argue that socialism was more moral than capitalism. This aligns with the historical pattern of some socialist individuals and groups who have sought to harmonize their economic and social policies with religious ethics, often aiming to appeal to the moral conscience of believers.