Great Apostasy

The Great Apostasy, according to some religious groups, is the perceived fallen state of traditional Christianity, especially the Roman Catholic Church, because it allegedly allowed traditional Greco-Roman culture (i.e, Greco-Roman mysteries, deities of solar monism such as Mithras and Sol Invictus, and idol worship) into the church. In short, in their opinion, the church has fallen into apostasy. They feel that to attract the pagans to nominal Christianity, the Catholic Church took measures to amalgamate the Christian and pagan festivals so pagans would join the church; for example, bringing in the pagan festival of Easter as a substitute for the Pasch or Passover, although neither Jesus nor his Apostles enjoined the keeping of this or any other festival.

They consider the papacy to be in full-blown apostasy for allowing pagan rituals, beliefs and ceremonies to come into the church, having those who pointed out its apostasy persecuted and killed and never repenting of or fully admitting the true extent of its actions.