People should know that false teachers will teach anything they believe, and not from the Bible. People also should look at the preachers their behaviour and see if they have the Holy Spirit in them, following, living according and teaching the words of the Holy Bible. Often their way of talking, using a language which is not according the way Jesus would talk shall dismantle them and should be a sign for you that they are not the right one to follow.
Before calling a church or religious group a "cult" or "sect" one should seriously examine and clarify what one means with those qualifications.
Lots of times Christadelphians are called a cult group, but they are a religious group where no specific human being is venerated and no human beings worshipped like in other religious Christian groups which are not called cults, like the Catholic Church where people pray to 'saints' and worship in front of statues.