grammaticality - "You just can't" vs. "you can't just "

I'm a bit confused about this. Which expression is correct?

You can't just do that.

or

You just can't do that.

I'm trying to say:

You can't just bash an ideology because of what someone has said/done.

Answer

As with only, one should exercise care in carefully placing just. In your sentence, you want:

• You can’t bash an ideology just because of what someone has said/done.

Because you want to be perfectly clear that just applies to because.

In the original pair of question, this one:

• You can’t just do that.

Applies just to do, whereas this one:

• You just can’t do that.

Applies just to can’t.