Final answer:
The specific three sub-stages of the theological stage are not provided in the details given. Additional context is needed to accurately determine the sub-stages.
Step-by-step explanation:
The three sub-stages of the theological stage are not explicitly outlined in the information provided. However, if we consider the theological stage in the context of religious development and 'the beginning of orthodoxy' during the second and third centuries as mentioned, we can infer that the three sub-stages might refer to the development of religious thought and the establishment of doctrinal principles such as the Holy Trinity in Christianity. Thus, the theological stage could be subdivided into early theological development, consolidation of orthodoxy (including the formalization of beliefs such as the Holy Trinity), and the establishment of religious practices and rituals (like Baptism, Communion, and Confession).
Unfortunately, the texts provided do not offer a clear breakdown of the three sub-stages of the theological stage, which suggests that additional context from the book or source material would be necessary to provide a precise answer.