The crack of doom

Meaning

The sound that heralds the day of the Last Judgment, when God will decree the fates of all men according to the good and evil of their earthly lives.

Origin

From Shakespeare's Macbeth, 1605:

MACBETH: Thou art too like the spirit of Banquo: down!
Thy crown does sear mine eye-balls. And thy hair,
Thou other gold-bound brow, is like the first.
A third is like the former. Filthy hags!
Why do you show me this? A fourth! Start, eyes!
What, will the line stretch out to the crack of doom?

The notion of having to account for one's earthly deeds is expressed in many parts of the Bible; for example, in Matthew 12.36 (King James Version):

But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment.

See other - phrases and sayings from Shakespeare.