I wouldn’t call them a cult - they have some elements like a cult, but I want to reserve the word cult to something a little stronger/less moral. Cults tend to abuse children (child abuse is everywhere, but cults it would be part of them) or commit mass suicide.
Like Mormons, many christian groups consider the theological differences strong enough to not call them christian. Of course Christian is a label that was applied by outsiders to talk about this new sect and so I guess really what counts could be how outsiders think of them.
Take your pick. You can argue either way.