The phrase has become commonly used as a title for works of popular culture, in some cases to describe the act of gunfighting. It also means that whether one is alive (the quick) or in the afterlife (the dead), God will still judge the sins of the individual.
LAERTES (after leaping into the grave of Ophelia):
Now pile your dust upon the quick and the dead,
Till of this flat a mountain you have made,
To o’ertop old Pelion,
or the skyish head Of blue Olympus.
- William Shakespeare’s Hamlet, Act 5, Scene 1
“For the time past of our life may suffice us to have wrought the will of the Gentiles, when we walked in lasciviousness, lusts, excess of wine, revellings, banquetings, and abominable idolatries: Wherein they think it strange that ye run not with them to the same excess of riot, speaking evil of you: Who shall give account to Him that is ready to judge the quick and the dead“.
King James Version, I Peter 4:3-5