> My serious question is this: how do we stop terrorism and criminals when they have access to military grade encryption technology?
You don't and technology has nothing to with it either.
Terrorism is as old as government itself and doesn't need the internet in order to function.
Radicalisation takes place in many places and law enforcement as well as national intelligence agencies have put their focus away from good old-fashioned police work, infiltration and observation towards telecommunication.
There was no internet in 1972, yet the Munich Olympiad Massacre happened. Just take a look at a random year pre-internet: https://en.wikipedia.org/wiki/List_of_terrorist_incidents_in...
Terrorism is neither a new phenomenon nor boosted by the internet - it's our perception that has been boosted. Today, every single incident is instantly known and international news.
People just seem to have forgotten that terrorism was pretty much part of daily life in past decades, too (the German version seems to be more complete, listing terror attacks without fatalities as well: https://de.wikipedia.org/wiki/Liste_von_Terroranschlägen_im_... )
Exchange of information and coordination doesn't require encrypted internet technology at all.
In Spain, ETA declared a new ceasefire in 2010 presumably because political parties with ties to them were banned and a leading member died (of undisclosed cause).
In Germany, the left-wing terror group RAF disbanded in 1998 after key members had been arrested and the 1991 collapse of the Soviet Union, Germany reunification and the subsequent disintegration of the communist bloc basically robbed them of their ideological base, support structures and legitimisation.
The whole IRA business seemed somewhat sorted with the Good Friday Agreement in 1998, but in the aftermath of Brexit tensions seem to start to raise again.
Basically, politics, old school police work and having a close eye on organisations are much more effective than mass surveillance and technology.
You won't be able to catch every "lone wolf" - be that the right-wing extremist who starts a mass shooting or the Islamic extremist who randomly stabs people.
But you can avoid a lot of it by enforcing a zero-tolerance policy (most of the recent extremist terrorists had a criminal record), deporting criminals, shutting down organisations that support terrorism (including mosques if applicable) and drying out sources of finance.
Mass surveillance, bans, and thought crime (i.e. "hate speech", which is basically a blanket term for "I am offended" these days) are not viable solutions.