Kuv, what you heard is haskalah-based orthopraxy, where your actions count more than your beliefs.
Tzadik beemunaso yichyeh; hen yiras Hashem for starters. The Torah s actions/mitzvos are meant letzaref es habros, chazal say. The zohar says that the mitzvos are “aitzos” to become close to Hashem. The gra writes that fixing one’s middos is tachlis hachaim.
Doing an aveirah lands a person in gehinnom. Having hererical ideas makes him lose olam haba. Middos are also stuck with the person the way they were when he died.
The early rishonim spent most of their seforim on hashkofa.
I can go on and on.
Short version; the shiur rabbi speaker person is puppeting maskilim who wanted to keep mitzvos without penimius or an emphasis on emunah.