Be knocking on heaven's door informal verb phrase
To say that someone is dying or approaching or very close to death.
Peter fought his disease bravely, but I'm afraid he's now knocking on heaven's door.
Can you come back home to meet our father, Mina? He is knocking on heaven's door.
To die or pass away
Used to refer to a place where everyone is happy or finds what they want
1. To pass away
2. To depart suddenly
1. One's success has gone down or ended.
2. One has passed away.
The verb "be" should be conjugated according to its tense.
Daughter: So I really want all my friends to have a great time. I was thinking it would be a good idea to have some candy out on the tables for people to snack on.
Mother: Well, if you want them to really enjoy themselves, candy is dandy but liquor is quicker.