Go underground.
We've done it countless times throughout history.
Michael O'Brien has been alluding to this scenario for years. I haven't read anything beyond "Father Elijah" but I gather he has known the repression was coming for a long time. Perhaps his books hold the clue.
Frank
Now I know what that tunnel was for they found at the border. It was for escaping Catholics. An underground railroad against socialism.
There will come one final time when hiding is not the appropriate response. It would only encourage and strengthen the evil opposition, such that The +Church could actually be exterminated. When that time comes (I don't know when) we need to confront the source of evil and, if necessary, destroy it.
And we're still here whilst those regimes are dust and ash. *Nods* God is good.