Eh, even when asked specifically to show it's work GPT-4 still frequently makes calculation errors. It's just one of the limitations of current LLMs, and can easily be solved by integration with Wolfram, or even just a basic calculator.
The person you linked (Sam Harris) is actually one of the leading voices advocating for spirituality without religion. He wrote about it in his book Waking Up: A Guide to Spirituality Without Religion.