All cantrips deal no damage on a miss or a successful save - it's a feature of cantrips in general, as the lowest tier of infinite cast spells.
Some classes can get class features that cause cantrips to act more like levelled spells (wizard, mainly), that will let them deal half damage on a save/miss, but that's a specific subclass feature.
That's theoretically true, but it being a dex save, it seems to never hit?
I've done extensive testing with only 1 successful attempt. Any other old wizard cantrip hits at least 60-75% of the time. And/or does more damage. I've looked it up by now and some people say they also can't get it to even hit. It's one redeeming feature is that you theoretically don't need to see enemies to cast it. However, that's also inconsistent! If it's possible, a PC will waste all movement to cast sacred flame. I don't get a say so, despite it not being necessary. Then you're stuck with them on a terrible spot on the battlefield and no movement.
There is literally no benefit to it in Bg3. It's better to do nothing at all than to cast sacred flame at low levels. Only a couple hours in, you already have better spells. It's ridiculous.
