Do false churches already exist?
Didache: https://legacyicons.com/content/didache.pdf , https://christianhistoryinstitute.org/study/module/didache/

Vatican-Ecumenical: https://www.usccb.org/committees/ecumenical-interreligious-affairs/vatican-ii-and-ecumenical-movement?utm_source=chatgpt.com

Dictionary of Ecumenical:  ...