How do they know the sniper was Israeli? For all we know, hamas might have decided to shoot those Christian women to make Israel look bad, and I doubt they give a damn about Christians any ways. But if it was indeed a Israeli, it might have been a tragic mistake. OTOH, if it was deliberate, the sniper should be prosecuted.
The accusation has been out there for two days, and AFAIK has not been denied by Israeli authorities. If this was a false flag, let them say so on the record.