God help (one) spoken language informal
Used when you want to warn someone that he or she will be in danger or that something bad will happen to them
God help us if this plan doesn’t succeed.
God help you if he finds out you lied to him.
To give someone information
I warned you in advance, especially about a negative consequence.
To warn someone that they are responsible for their actions, plans.
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.