The list of severe sins in Torah are not generally known. Good examples are lashon hara [slander] and bitul Torah [not learning Torah when one is able]. In neither of these am I a shining example of how to be careful. But I try. Sadly most public discourse is lashon hara. But there is permission because of the need to warn people about danger. And in fact I depend on that permission. But even legitimate warnings are ignored in the tidal wave of lashon hara that affects all public discourse. 

As for bitul Torah I am no shining example, At some point, I discovered the opinion among some Rishonim about Physics and Metaphysics --being in the category of learning Gemara,

But you could claim that that is somewhat of a stretch. -Especially when it seem to be in direct contradiction to open gemaras about staying away from Greek wisdom. Still I have got a few poskim/authorities to depend on,  and that is enough for me. [However, I do not expand the definition of learning Torah infinitely, but rather confine it to the Oral Law (as given over through the sages of the mishna and gemara), and the Written Law [Old Testament]]