Final answer:
P. C. Nelson's Bible Doctrines became a popular manual due to its plain language and practical understanding of AG beliefs, aligning with the history of Christian literature and the propagation of Protestant theology through accessible media.
Step-by-step explanation:
The popularity of P. C. Nelson's Bible Doctrines can be attributed to a variety of factors deeply rooted in the history of Christian literature and the propagation of religious teachings. The manual, produced by Gospel Publishing House, became a popular resource because it was written in plain language that was accessible to readers seeking a practical understanding of Assemblies of God (AG) beliefs. This simple, clear presentation made it useful for ministerial training and provided a standardized set of teachings that helped to counter false doctrines prevalent in the 1930s. The historical context of the Protestant Reformation and the emphasis on scripture as the sole source of religious authority, popularized by figures like Martin Luther, along with the advent of the printing press, greatly influenced the dissemination of religious texts and the push for literacy so that individuals could read the Bible themselves. The rise of printmaking in Europe facilitated the spread of Protestant theology through accessible visual media. Furthermore, the early Christians' commitment to crafting a unified narrative and identity through theological writings laid the groundwork for later texts like Nelson's manual to establish a consensus on doctrine.