I cannot see the future, therefore I do not know for certain that harm will be caused. However, I have every reasons to thinkn that this will be the case.
What reasons? You've cited examples of parents who hold views far more dogmatic than TL does, for instance your example of "theistic parents witholding medical treatment." Has TL made any comment you feel to be anti-science or anti-medicine? To the contrary, he accepts modern medicine to the same degree you do.
You've made the gross and inapproptiate error of assuming that all theists think alike, when in fact the term "theist" covers only one thing - a belief that god exists. That's it. That's all you have to believe to be a theist. As for the rest there's as great a diversity of opinion amoung theists as there is amoung atheists.
Religious PARENTS are harmful to children.
Woah, that's something way different than what you've been saying. Sure, some religious parents have been harmful to their children. Some atheist parents have been, too. But what you're saying is tantamount to saying "Australians abuse their children, so no Australian can be allowed to be a parent."
Moving the goalposts isn't going to help you here. You need to prove that religion is the factor that leads to abuse - that religion is itself abusive - in order to support your statements. Simply citing parents who, while religious, hold views drastically different than the views TL has espoused is irrelevant and fallacious.
I maintain the TL's expressed intent to isolate themselves among a like-minded community that will never challenge any of this dangerous dogma
What dogma, exactly? The only dogma I've heard so far has come from you, assuming the worst about TL's beliefs despite his statements to the contrary.