Yes they are extremist that will almost too gladly sacrifice many of their own members following some ill contrived idea that the bible forbids blood transfusions,, by using dubious scriptural interpretations and have no remorse. I call that extremist will no exaggeration.
Lets not get started on dismembership from the cult if one who votes, gets involved in politics, joins any one of a host organizations that the WT is at odds with, or someone choses not to believe everything the Governing Body teaches, and the list goes on and on so yeah they are pretty God dam extreme and really very very cuckoo for Jehovah the corporation's mascot.