"被邪教所支配" can be translated into English as "be dominated/controlled by a cult" or "fall under the sway of a cult".
Here are two example sentences:
1、 He was completely dominated/controlled by a cult and lost his own judgment.
(他被邪教所支配,完全失去了自己的判断力。)
2、 She fell under the sway of a cult and started to follow its bizarre teachings blindly.
(她被邪教所支配,开始盲目地遵循其荒谬的教义。)