Some who deny the doctrine of original sin cite Ezekiel 18 as a refutation of the doctrine. I will make the case for it here - first by discussing what original sin is, then discussing Scripture passages which teach the doctrine of original sin, and finally by showing why Ezekiel 18 does not refute the doctrine of original sin.
An article from the Catholic encyclopedia on original sin can be read ( http://www.newadvent.org/cathen/11312a.htm ) which I think will be helpful. Also, while I recommend reading the entire article from the Catechism ( http://www.vatican.va/archive/ccc_css/archive/catechism/p1s2c1p7.htm ), I'll simply cite two paragraphs.
"404 How did the sin of Adam become the sin of all his descendants? The whole human race is in Adam "as one body of one man". By this "unity of the human race" all men are implicated in Adam's sin, as all are implicated in Christ's justice. Still, the transmission of original sin is a mystery that we cannot fully understand. But we do know by Revelation that Adam had received original holiness and justice not for himself alone, but for all human nature. By yielding to the tempter, Adam and Eve committed a personal sin, but this sin affected the human nature that they would then transmit in a fallen state. It is a sin which will be transmitted by propagation to all mankind, that is, by the transmission of a human nature deprived of original holiness and justice. And that is why original sin is called "sin" only in an analogical sense: it is a sin "contracted" and not "committed" - a state and not an act.
405 Although it is proper to each individual, original sin does not have the character of a personal fault in any of Adam's descendants. It is a deprivation of original holiness and justice, but human nature has not been totally corrupted: it is wounded in the natural powers proper to it, subject to ignorance, suffering and the dominion of death, and inclined to sin - an inclination to evil that is called concupiscence". Baptism, by imparting the life of Christ's grace, erases original sin and turns a man back towards God, but the consequences for nature, weakened and inclined to evil, persist in man and summon him to spiritual battle."
In short, Adam and Eve were created in a state of perfection and had in their souls the life of God. Through their first sin, they lost that state of perfection, and thus all their descendants inherit an imperfect state of existence. By way of imperfect analogy, consider a man who was a billionaire. Through foolish decisions he squandered all of his money and became poor. He then had children with his wife. The children are born into poverty. Why should they be born into poverty? They did not make foolish decisions and squander money. Shouldn't they also be billionaires as their father was before he made foolish decisions? But because their father lost what he had, he was unable to pass on an inheritance of what he formerly had. It is similar with original sin. Original sin is an inherited lack of that original state of perfection - a lack of the life of God in their souls.
Romans 5:12-21 "Therefore, just as through one person sin entered the world, and through sin, death, and thus death came to all, inasmuch as all sinned— for up to the time of the law, sin was in the world, though sin is not accounted when there is no law. But death reigned from Adam to Moses, even over those who did not sin after the pattern of the trespass of Adam, who is the type of the one who was to come.
But the gift is not like the transgression. For if by that one person’s transgression the many died, how much more did the grace of God and the gracious gift of the one person Jesus Christ overflow for the many. And the gift is not like the result of the one person’s sinning. For after one sin there was the judgment that brought condemnation; but the gift, after many transgressions, brought acquittal. For if, by the transgression of one person, death came to reign through that one, how much more will those who receive the abundance of grace and of the gift of justification come to reign in life through the one person Jesus Christ. In conclusion, just as through one transgression condemnation came upon all, so through one righteous act acquittal and life came to all. For just as through the disobedience of one person the many were made sinners, so through the obedience of one the many will be made righteous. The law entered in so that transgression might increase but, where sin increased, grace overflowed all the more, so that, as sin reigned in death, grace also might reign through justification for eternal life through Jesus Christ our Lord."
So now a few comments on this passage. Now the first two sentences are very clear: sin entered the world through Adam's first sin, and this sin resulted in death for all mankind. You might try to argue that Paul is saying that it is a result of each man's own sin because he says "inasmuch as all sinned." So in order to clarify his position, he says that this is not the result of each man's own sins when he says that this applies "even over those who did not sin after the pattern of the trespass of Adam." Paul also argues that it could not have been due to each man's sin because "sin is not accounted when there is no law" but yet yet the results of Adam's sin continued even for those not under the law. So what Paul means by "inasmuch as all sinned" is that all humanity, at least in a sense, participated in the first sin of Adam. This idea is not contradictory to Scripture but is corroborated by Hebrews 7:9-10 "One might even say that Levi himself, who receives tithes, was tithed through Abraham, for he was still in his father’s loins when Melchizedek met him."
Now in the second paragraph Paul is really driving home a point. He's drawing a direct comparison between Adam and Jesus. He says "For just as through the disobedience of one person the many were made sinners, so through the obedience of one the many will be made righteous." So if one wishes to argue that Adam's sin did not cause any actual effect on his descendants and that the first sin of Adam simply caused his descendants to sin by following his example (he just "got the ball rolling," so to speak), then by this passage one must, in order to be consistent, also conclude that Jesus' death and resurrection really has no effect either; Jesus simply gave a good example for us to follow, and we gain our own salvation by following Jesus' example. So logically a denial of the doctrine of original sin necessitates a denial of Jesus' atonement for sin.
So what about Ezekiel 18? Now because this post is already long, I won't quote it here, but I suggest you read Ezekiel 18 in its entirety ( http://www.usccb.org/bible/ezekiel/ezekiel18.htm ). In fact, this is one of those cases where the context of the whole book of Ezekiel is necessary for a proper understanding. And while I won't really get into it here, you may also want to read Jeremiah 31:27-34.
Ezekiel 18:1-4 "The word of the LORD came to me: Son of man, what is the meaning of this proverb you recite in the land of Israel: “Parents eat sour grapes, but the children’s teeth are set on edge”? As I live—oracle of the Lord GOD: I swear that none of you will ever repeat this proverb in Israel. For all life is mine: the life of the parent is like the life of the child, both are mine. Only the one who sins shall die!"
The whole of Ezekiel 18 is addressing what is stated in these first 4 verses. Ezekiel prophesied during the time of the Babylonian captivity. The descendants of those who were actually deported to Babylon lived at this time. Though they lived in the same sinful manner as their parents, they believed themselves to be righteous and thought they were unjustly being punished by God for the sins of their ancestors. In other words, when they spoke the above proverb, they were complaining against God and accusing him of being an unjust judge. The remainder of Ezekiel 18 is God explaining to the Israelites that he was indeed being just; He was punishing them for their own sins and not for the sins of their fathers. Understood in this light, it can be seen that the whole discussion of Ezekiel 18 is specifically geared towards answering the Israelites' complaints against God and is not relevant to the doctrine of original sin.
For another writer's take on Ezekiel 18, I suggest reading http://turretinfan.blogspot.com/2008/04/misuse-of-ezekiel-18-especially-ezekiel.html and also the commentaries on http://bible.cc/jeremiah/31-29.htm and http://bible.cc/ezekiel/18-2.htm as well as the relevant cross-references.
