Memoriales perdidos (1985)

In the 16th century, an envoy from the pope and the king of Spain arrives in New Spain to deal with the case of Augustinian Alonso, in a state of autism by ingesting herbs given to him by the native Tlacuilo Camistli, who has been accused of sorcery. The envoy speaks with him and asks for the grass and ingesting it can communicate with Alonso, who contemplates in an internal vision a shining light that reflects the divine goodness. The envoy gets a dagger to Camistli and he takes his life. The envoy destroys the memorials he would send to Europe and decides to stay.

Unfortunately the movie Memoriales perdidos is not yet available on HBO Max.