God help someone idiom (also heaven help someone)
（某人）全靠老天保佑了（强调危险或严重性）
used to give force to a statement of the danger or seriousness of a situation or action
God help us if they attack now while we're still unprepared. 如果他们在我们还没做好准备的情况下即刻发起进攻，那就只好靠上帝帮忙了。