Gabriella,
It’s “problematic” when lies are taught to children, not that there's a diversity of beliefs.
I happen to think that teaching lies to children is a bad idea. If you don’t, then so be it.
As I said I think teaching beliefs to children - interpretations of experiences and personal perspectives - is part of being human. If you want to label these interpretations and perspectives as "lies" so be it. I don't intend to generalise that teaching children beliefs or "lies" if you prefer to call them that, is problematic.
I think some beliefs can be problematic. I also think some generalisations - you can call generalisations "lies" as well if you prefer - can be problematic.
For example certain beliefs about the superiority of liberal democracies can cause people to turn a blind eye to the exploitation and the export of death and destruction that those liberal democracies have inflicted on foreign communities.
Possibly it can be useful to look at the number of people negatively affected by a belief in order to form an opinion on how problematic that belief is. Having said that it is often impossible to quantify the negative impact of a particular belief as it is impossible to isolate the cause and effect to single beliefs.
I don't really have the data to decide if interpreting experiences to form a belief in a soul is particularly problematic. On the other hand I could quantify to some extent the negative impact of a belief that it is morally justified in certain circumstances to bomb innocent people to achieve political aims - whether that is the political aims of terrorists or governments. And yet it seems part of being human that people continue to teach children beliefs that justify such actions.