>> Even ones that do are protected under the First Amendment. Actually engaging in violence or harm is illegal and not constitutionally protected, of course. But simply advocating for harm against non-believers does not violate freedom of religion. If it did, we would have to outlaw Islam, Judaism, and other religions. <<
"Inciting" violence is not protected speech, as per Brandenburg v. Ohio - https://en.wikipedia.org/wiki/Brandenburg_v._Ohio
While many religions' ancient sacred texts have passages that are not kind to outsiders, modern practices mostly distance themselves form such passages, framing them as historic artefacts from a different time. One popular and fast-growing religion, however, does currently advocate and promote violence against infidels, heretics, and apostates. In itself, this is not "crossing the line", but when incidents of actual violence are considered in aggregate, a reasonable person might begin to doubt the legitimacy of such religious teachings, and consider it more of a dangerous cult.
>> Speech, religion, assembly, press, and to petition the government for a redress of grievances (and I did not have to look them up) <<
Either you're extraordinarily well versed in the US Constitution, or you're lying.
>> That is true. However, again, simply having a teaching that advocates for violence against non-believers does not mean the government can ban a religion. Otherwise, it would require that both the Koran and the Bible be prohibited, since both contain verses which promote violence and death for non-believers. <<
"The government" can and should take legal action against individuals and/or groups who repeatedly "incite" violence. Whether it's an outlaw biker-gang or a registered religious organisation does not and should not matter.
>> The link you provided doesn't really help your argument, since it acknowledges that what a cult is cannot always be clearly defined. <<
Do you disagree with the assertion, that a religion which advocates for killing infidels, heretics, and apostates is not a cult? While there's certainly no legal definition of a "cult", (I'll say it again) "the government" can and should take legal action against individuals and/or groups who repeatedly "incite" violence. Whether it's an outlaw biker-gang or a registered religious organisation does not and should not matter.