This should probably be green and white or probably just white.

I considered white-green until I remembered that "Spells and abilities your opponent's control can't cause you to sacrifice" seems to come from exclusively green rather than white. Tajuru Preserver being the first card to have that ability. Sigarda, Host of Herons and Tamiyo, Collector of Tales, both multicolor, show that that green is the necessary color for this ability, since their other colors differ. Fog is a very green effect.

Green and white have been pushing Holy Day and Fog back and forth between themselves for a while now, and currently it is in green, because the effect is more useful in green.

I'd say the effect could in its entirety appear on a monocolored white card, but it is just as fine on this monocolored green card.

"Noble Piety" just sounds more like a white cardname. Otherwise the card is fine.

The damage prevention should end in "this turn" though and the anti-sacrifice effect could easily be worded the same for consistency's sake.