David Webber - Safehold series. https://en.wikipedia.org/wiki/Safehold
The first book is Off Armageddon Reef - https://en.wikipedia.org/wiki/Off_Armageddon_Reef
In the 24th century, 8 million people flee to distant Safehold after barely escaping from the destruction of civilization by a genocidal alien foe, the Gbaba. Because the enemy tracked signs of advanced technology to hunt down other emergency colonies, the plan is to enforce a pre-industrial society until the danger passes. Administrator Eric Langhorne, a megalomaniac and neo-Luddite, instead has the colonists' memories erased and replaced with the belief they are the first humans, "Adams" and "Eves," the creations of God upon Safehold with "Archangel Langhorne" anointed as prophet and leader of the Church of God Awaiting.