What sets the Relación apart from most of its contemporaries is that Molina wrote down Quechua. The prayers he records were spoken at the great festivals, and having them in the language they were said in lets modern scholars examine their form, their address to the creator and the ancestors, and their vocabulary, rather than reading a Spanish priest's summary of what he thought they meant. Comparison with the Huarochirí Manuscript, the other major early Quechua religious text, is possible only because both exist. It also lets the reader see where Molina's Spanish gloss quietly does theological work on the Quechua next to it.
The survival of the text is precarious. There is one manuscript copy, in Madrid, made after his death; his other writings, including what appears to have been a longer historical work, are lost. So the Andean ceremonial year rests on a single copy of one report by one priest, which is worth remembering whenever an account of Inca religion presents the calendar with confidence. Molina's value is not that he was neutral, because he was not, but that he was close, competent in the language, and interested in accuracy for reasons of his own. A reader meeting Inca religion for the first time should know that its ceremonial year is largely one man's report, and that the confidence with which the calendar is usually presented is borrowed from him rather than independently established.