"Most of the Christians at last consented to lower their standard, and a union was formed between Christianity and paganism. Although the worshipers of idols professed to be converted, and united with the church, they still clung to their idolatry, only changing the objects of their worship to images of Jesus, and even of Mary and the saints. The foul leaven of idolatry, thus brought into the church, continued its baleful work. Unsound doctrines, superstitious rites, and idolatrous ceremonies were incorporated into her faith and worship. As the followers of Christ united with idolaters, the Christian religion became corrupted, and the church lost her purity and power. There were some, however, who were not misled by these delusions. They still maintained their fidelity to the Author of truth and worshiped God alone. GC 43.1"
"And he cried mightily with a strong voice, saying, Babylon the great is fallen, is fallen, and is become the habitation of devils, and the hold of every foul spirit, and a cage of every unclean and hateful bird."
The EGW passage describes the corruption of the church through the introduction of pagan practices, which parallels the description of Babylon in Revelation 18:2 as a place filled with unclean spirits and idolatry. Both passages depict a state of spiritual defilement and apostasy.