Alright, I think I read these back in the 80s or early 90s. Every search I've tried keeps bringing up newer books that aren't even close to what I'm looking for, so I'm hoping crowd sourcing it here might work better.
The series starts with the main character being part of an order of psychic monks who raise telepathic moose in what once was Canada. The setting is post nuclear apocalypse, with America only recently reaching levels of nuclear radiation low enough to travel through, and even then only if you know what areas to avoid; while not explicitly stated, it seems that even in a nuclear apocalypse, the Canadians are too nice for people to attack.
The main character encounters an enemy psychic who had come up from America, prompting him to begin a journey to find out more about what life continued to survive to the South. Along the way, he runs into an order who refer to themselves as Eleventhers. This order formed from scientists who survived the nuclear armageddon in bunkers and swore to add an eleventh amendment to the biblical ten: Harm not the Earth nor any of the creatures who walk thereon. They(and their descendants) have been doing everything they can to help the Earth recover from all of the damage humanity had dealt it.
The series, as I recall, contains relatively normal humans who were still in the mindset of 'whoever has the biggest/best weapons win,' who are trying to gain control of some of the unlaunched nuclear warheads; twisted and deformed critters roaming a corrupt desolation; and a giant monstrosity aware that it gained sentience through the agency of nuclear induced mutations and which wants to set off more warheads in the belief that doing so will make it stronger.