Is original sin an unjust doctrine?

Some people object that the doctrine of original sin is unjust, for it holds other people responsible for Adam's (and Eve's) sin to the extent that they're condemned to hell for something they themselves didn't do. In particular, the objectors say, infants who die are condemned to hell as a result, even though they have not yet consciously sinned.

This version of the doctrine is not held by all evangelical Christians and is not an essential belief of Christianity. Calvinists appear to believe that people deserve hell in part because of original sin, but many believe that infants who die are among the "elect" and are therefore saved by God's grace (see Infant Salvation by Lorraine Boettner). Other Christians, including myself, believe that we suffer the effects of Adam's sin - we are born with a sinful nature and will experience physical death - but we're not individually condemned to hell because of Adam's sin, for, "The soul who sins is the one who will die. The son will not share the guilt of the father, nor will the father share the guilt of the son" (Ezek 18:20).

Other responses (offsite)

• A Look at the Doctrine of Original Sin by J.P. Holding argues for the view that Adam's sin and punishment established a precedent for the punishment of our own sins.
• Are We Punished For Adam's Sin? by Matthew J. Slick

• Born Guilty by Matt Perlman - A theological defense and explanation of "imputed" sin vs. "original" sin
• God is unfair to blame us for Adam's sin by Ross A. Taylor - a briefer defense of this view

• Does God punish children for their parents' sins?