What is the meaning of let the dead past bury its dead?

Answer 1

This means that he should not worry about burying his dead relative, but to do the work that the Lord had commanded him to do and let his relatives or the villagers worry about burying his dead relative. The lord is saying that all will die eventually, hence "Let the dead bury the dead".

Most commentaries suggest Jesus meant, "Leave the (spiritual) dead to bury the (physical) dead" (Fitzmyer 1981: 836; Liefeld 1984: 935).

In addition to its biblical context stated above it is also used my Marx in The Eighteenth Brumaire of Louis Bonaparte. Marx uses it in the context of the social revolution of the 19th century. He utilizes this biblical quote to emphasize the idea that the revolution must not rely on the social models of the past in order to derive its roots, but rather must reject all past illusions (such as religion or bureaucracy) and instead build itself in the present as a modern revolution that springs forth a new system that does posses the faults of past constructs. So in a sense Marx is calling upon the new revolution to remove itself from the historical patterns that have led to the reoccurring rise of the bourgeois.

In this sense "let the dead bury the dead" means let the flawed bourgeois social systems die once and for all for their repetitive flaws (let the dead just die, do not keep resurrecting them in the present social system) (Marx 1852: 595)

Answer 2

This phrase means to move on from past events or mistakes and not dwell on them. It suggests that we should focus on the present and future rather than being held back by past regrets or sorrows.