Heaven only knows how we’d all cope without Tim Bowen’s informative articles on idioms!
If we move heaven and earth to avoid something happening, it means that we do everything possible to prevent this happening.
A marriage or relationship made in heaven is very happy and successful, as in ‘The merger of the two companies wasn’t exactly a match made in heaven’.
If you enjoyed something very much, you can say I thought I’d died and gone to heaven, as in ‘A two-week all expenses paid holiday in Mauritius! I thought I’d died and gone to heaven’.
If the heavens open, it starts raining very heavily, as in ‘We were just walking home from the pub when the heavens opened and we got absolutely soaked to the skin’.
The expression heaven help us (or them, him, etc.) can be used in two ways. It can be used for saying that you hope something will not happen, as in ‘There’s no fire escape in the building. Heaven help us if there’s a fire’. It can also be used for saying that if something bad happens, the result will be very bad for the person or persons mentioned, as in ‘They are armed and dangerous. Heaven help anyone who tries to stop them’.
The expression heaven only knows is used for saying that you do not know something or you cannot imagine it, as in ‘They’ve not only stolen the car, they’ve taken our credit cards and money too. Heaven only knows how we’re going to get home’.
Finally, if something stinks to high heaven, it smells very, very bad.