ISTA has been citing cult expert Dr. Steven Hassan's work to say they aren't a cult. See the video response of Dr. Hassan: Also see the facebook post of the statement by the Israeli Center for Cult Victims regarding ISTA with interesting information in the comments:
Forum: "Cults," Sects, and "New Religious Movements"

A link to the Israeli Center for Cult Victims' statement regarding ISTA: English version PDF is available here: I find ISTA's response to be weak and misleading.
Forum: "Cults," Sects, and "New Religious Movements"

Hi. ISTA is, I believe, definitely a cult. Some articles came out recently: 1. 2. 3. There is a large number of complaints made against ISTA by many people and mainly young women. It's really terrible. I have friends that were harmed. There is a dedicated Facebook group against ISTA with hundreds of people in it. I would love to connect and share information.
Forum: "Cults," Sects, and "New Religious Movements"