Thalnazpic christendom (Universal in Etruscan) is this thalnazpic's catholic faith. It is a remnant of the Etruscan Empire of the classical age. The Aranthurian faith is somewhat politically similar to the protestant faith, although differ wildly in theology - and has existed far longer. Etruscan religion is obviously not super well known but given the potential time frames your thinking it could work and it can just creative licensing on that. Etruscans which for whatever reason have been placed on the most Earth-like planet in the system along with fauna and flora around 2000 years ago.
The Etruscan history and religion are relatively well know, since the Romans took a significant part of their mythology and there is a "History of Etruria" written by the emperor Claudio (Claudio Tiberio Augusto Germanico ... and something else).
It is uterly unrelated to christianity in any sense - the Etrurian gods were pretty much opaque and unknown and uncommonly for the age, not that much related to nature nor humans.