There are three kinds of Christians Extremists, and all three are positive:

1) those who gave away all they had and dedicate their lives to aid their fellow men.
2) those who devote to a life of seclusion and prayer with a group of others, for the kingdom of heaven sake: Monks/Nuns.
3) those who devote to a life of absolute seclusion and prayer, for the kingdom of heaven sake: Hermits.

Why are these positive? Because they do not inflict harm upon anyone with their devotion.