Their brethren? I believe you are uneducated if you are referring to the group I assume you are. Especially given the politics of the region and the differences/animosity between those groups
Their important common denominator is "we believe in bringing about submission to Allah at the point of the gun". I would advise any "unbeliever" to stay the hell away from any such group.
When Hamas lets Christians live, they are doing what Islam considers right. Outright pagans (polytheists) would be a different story.
Still, they enforce Islamic law where they rule. You cannot be openly gay, you cannot openly proclaim that you no longer believe in Allah (apostasy), a Christian man cannot marry a Muslim woman.
The fact that some other fundamentalists go further than Hamas doesn't make Hamas non-fundamentalists.