According to Christian denominations, why are we all cursed for Adam's sin and is that fair?

We do not suffer death because of his sin, we suffer death because of our sins, and because we are heirs to a fallen state, which is a necessary part of God's plan.

Why must we die? To the fulfilling of God's decree that if Adam were to eat of the fruit of the tree of knowledge of good and evil, "in the day that thou eatest thereof thou shalt surely die" (Genesis 2:17), and moreover the eternal law that "the wages of sin is death" (Romans 6:23). Adam and Eve shuffling off the coil of immortality by this choice and entering a mortal state meant that their posterity also would be mortal and susceptible to death. Our choice to sin (and all have sinned) is what makes our harvest one of death, consistent with the law of eternal justice. This helps to explain why Christ came, on both fronts of redemption as well as the Resurrection. The Fall brought with it other effects, which can be discussed in a separate thread.

The Scriptures teach that the plan of a limited period of mortal probation is merciful and essential to God's plan, implying that temporary separation from God's presence, trial, and death are all necessary according to God's own word:

"if it were possible that our first parents could have gone forth and partaken of the tree of life they would have been forever miserable, having no preparatory state; and thus the plan of redemption would have been frustrated, and the word of God would have been void, taking none effect.

But behold, it was not so; but it was appointed unto men that they must die; and after death, they must come to judgment, even that same judgment of which we have spoken ...

Now we see that Adam did fall by the partaking of the forbidden fruit, according to the word of God; and thus we see, that by his fall, all mankind became a lost and fallen people.

And now behold, I say unto you that if it had been possible for Adam to have partaken of the fruit of the tree of life at that time, there would have been no death, and the word would have been void, making God a liar, for he said: If thou eat thou shalt surely die.

And we see that death comes upon mankind, yea, the death which has been spoken of by Amulek, which is the temporal death; nevertheless there was a space granted unto man in which he might repent; therefore this life became a probationary state; a time to prepare to meet God; a time to prepare for that endless state which has been spoken of by us, which is after the resurrection of the dead." (excerpts from Alma chapter 12)

According to the Scriptures, it is necessary for us to die because it is necessary for us to have a time of testing, a time in which to prepare to meet God, without which we would be miserable forever, having no time to prepare. If eternity were already upon us, if we could not die, this would already be the case. The natural man could not be rooted out of our breast if we could not die. If we were to sin once in an immortal state, that sin would remain with us forever because the sin could not be purged, since eternal law requires that the punishment of sin is death. Therefore mortality and death are conditions of God's plan which we accepted in order that we might be prepared at the day of Judgment, and we are lawful heirs of death because of our individual sins, not because of Adam. Were it not for mortality and death, we could not be judged. Therefore Adam's fall plays an essential role in God's plan of salvation. My personal opinion is that transgression was not necessary, but falling from God's presence and the condition of physical death were necessary. I believe that anyone with access to the Scriptures can corroborate this.

My own philosophical argument: Finite probation is the only kind of probation.

This life is a test. We could not be judged if it were not a test; that would make judgment meaningless and immortality worthless. But what is a test? It is a condition where uncertainty is allowed, where temptation is permitted, and where changing one's eternal destiny is possible.

Let's suppose for a moment that the period of probation were infinite. Then we could say, even if we had wallowed in sin for our entire lives thus far, that we would repent at some future day, and serve God until the "end" thereafter. This results in a problem: The promise of future repentance given infinite time is not falsifiable. We could be quadrillions of years in and still be unsure of whether we even have it in ourselves to repent and serve God. We could always procrastinate, seemingly untouchable by God's final judgments. Moreover imagine the trials of Job, and consider if we could think of God as merciful or just if his torments had indeed endured forever. Even the Savior's sufferings, while infinite in intensity, were finite in duration. Thus it is possible to secure an eternal destiny and have final judgment administered unto perfection, given only a short span of mortality in which to prove ourselves. Were it otherwise, we could not be tested, no permanent change in our character could be enacted, and eternal justice and mercy would both be frauds, making the Savior's Atonement and resurrection null and void. Therefore the period of probation is necessarily finite, and mortality and death are merciful necessities in this process.

An exposition on inherited curses generally, and on fairness:

We became heirs to the curse of Adam willingly by choosing to come to this Earth to live under the conditions of mortality ushered in by the Fall.

The Scriptures contain many examples of curses and blessings that were decreed to persist across generations, usually by heredity, even as long as the Earth should stand in some cases.

Nonetheless it is vital to understand that such cursings and blessings often do not constitute final judgments, but are instead temporary ones, calculated for our salvation. They are designed both to inspire and to caution us to choose the right while our day of mortal probation lasts. The Lord will judge us with finality, and His word shall not pass away. It is worth the effort to identify whether a given curse or blessing has conditions attached to it, whether it applies to this life only, and whether it constitutes a final judgment from the Lord. My opinion is that most of the curses we discuss are of this temporal sort, and this of course includes the curse of Adam, from which we shall all be relieved through the Resurrection of Christ. What judgments remain into eternity are the ones we ought to concern ourselves about.

“But while one portion of the human race is judging and condemning the other without mercy, the Great Parent of the universe looks upon the whole of the human family with a fatherly care and paternal regard; He views them as His offspring, and without any of those contracted feelings that influence the children of men, causes “His sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust.” He holds the reins of judgment in His hands; He is a wise Lawgiver, and will judge all men, not according to the narrow, contracted notions of men, but, “according to the deeds done in the body whether they be good or evil,” or whether these deeds were done in England, America, Spain, Turkey, or India. He will judge them, “not according to what they have not, but according to what they have,” those who have lived without law, will be judged without law, and those who have a law, will be judged by that law. We need not doubt the wisdom and intelligence of the Great Jehovah; He will award judgment or mercy to all nations according to their several deserts, their means of obtaining intelligence, the laws by which they are governed, the facilities afforded them of obtaining correct information, and His inscrutable designs in relation to the human family; and when the designs of God shall be made manifest, and the curtain of futurity be withdrawn, we shall all of us eventually have to confess that the Judge of all the earth has done right.” (Teachings of the Prophet Joseph Smith, p. 218)

I take this to mean that no one should be envied, and no one can be spared the consequences of a Divine curse unless it pleases God to lift it. In the end we will see that God has done right in all things. Remember Aaron and Miriam, and Uzzah. Although the circumstances of life might seem unfair, God is perfectly fair.

Moreover we are not immune to the consequences of others' actions. We inherited the consequences of Adam's Fall (which are temporary) but we will not be held accountable for his or anyone else's transgression (which has eternal implications, since individual sin requires repentance by that same individual).

Nonetheless we do not subscribe to "original sin":

We believe that men will be punished for their own sins, and not for Adam's transgression. (Article of Faith 2)

I am a member of the Church of Jesus Christ of Latter-day Saints. My views are my own and where my own opinions have been shared they should not be taken as representative of the Church.

The question asks for information regarding the curse upon the first humanity (in Adam) 'according to Christian Denominations'.

[Paul, the Apostle, deals with this matter, in particular, in Romans 5:12-21 where he makes five comparisons (verses 15,16,17,18 and 19) contrasting what occurs under the Headship of Adam with what occurs under the Headship of Christ.]

CONTENT

1. The Westminster Confession
2. The Savoy Declaration
3. The Articles of the Gospel Standard
4. The Thirty Nine Articles of the Church of England

I - The Westminster Confession

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The Westminster Confession (and its adjunct, the Savoy Declaration) is accepted by many denominations as (or what they refer to as) a 'subordinate standard', that is to say subordinate to scripture (insofar as they understand that same scripture themselves).

Thus this statement is held by many within that which self-identifies as 'Christian'.

The Westminster Confession of Faith is a Reformed confession of faith. Drawn up by the 1646 Westminster Assembly as part of the Westminster Standards to be a confession of the Church of England, it became and remains the "subordinate standard" of doctrine in the Church of Scotland and has been influential within Presbyterian churches worldwide.

The Westminster Confession of Faith was modified and adopted by Congregationalists in England in the form of the Savoy Declaration (1658). Likewise, the Baptists of England modified the Savoy Declaration to produce the Second London Baptist Confession (1689). English Presbyterians, Congregationalists, and Baptists would together (with others) come to be known as Nonconformists, because they did not conform to the Act of Uniformity (1662) establishing the Church of England as the only legally approved church, though they were in many ways united by their common confessions, built on the Westminster Confession.

Wikipedia - Westminster Confession of Faith 1647

Chapter VI. Of the Fall of Man, of Sin, and of the Punishment thereof.

Our first parents, being seduced by the subtilty and temptation of Satan, sinned, in eating the forbidden fruit.(a) This their sin God was pleased, according to His wise and holy counsel, to permit, (b)having purposed to order it to His own glory.(a) Gen. 3:13; II Cor. 11:3.(b) Rom. 11:32.

II. By this sin they fell from their original righteousness and communion, with God,(c) and so became dead in sin, (d)(e) and wholly defiled in all the parts and faculties of soul and body.(c) Gen. 3:6, 7, 8; Eccles. 7:29; Rom. 3:23.(d) Gen. 2:17; Eph. 2:1.(e) Tit. 1:15; Gen. 6:5; Jer. 17:9; Rom. 3:10 to 19.

III. They being the root of all mankind, the guilt of this sin was imputed,(f) and the same death in sin and corrupted nature conveyed, to all their posterity descending from them by ordinary generation.(f) Gen. 1:27, 28 & Gen. 2:16, 17 and Acts 17:26 with Rom. 5:12, 15, 16, 17, 18, 19 and I Cor. 15:21, 22, 49.(g) Ps. 51:5; Gen. 5:3; Job 14:4, Job 15:14.

IV. From this original corruption, whereby we are utterly indisposed, disabled, and made opposite to all good,(h) and wholly inclined to all evil,(i) do proceed all actual transgressions.(k) -- (h) Rom. 5:6; Rom. 8:7, Rom. 7:18; Col. 1:21.(i) Gen. 6:5; Gen. 8:21; Rom. 3:10, 11, 12.(k) James 1:14, 15; Eph. 2:2, 3; Matt. 15:19.

V. This corruption of nature, during this life, doth remain in those that are regenerated;(l) and although it be, through Christ, pardoned and mortified, yet both itself and all the motions thereof are truly and properly sin.(m)--(l) I John 1:8, 10; Rom. 7:14, 17, 18, 23; James 3:2; Prov. 20:9; Eccles. 7:20. m) Rom. 7:5, 7, 8, 25; Gal. 5:17.

The Westminster Confession - Chapter VI

II - The Savoy Declaration

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'This was drawn up in October 1658 by English Independents and Congregationalists meeting at the Savoy Palace, London.' Wikipedia.

God having made a covenant of works and life, thereupon, with our first parents and all their posterity in them, they being seduced by the subtlety and temptation of Satan did wilfully transgress the law of their creation, and break the covenant in eating the forbidden fruit.

By this sin they, and we in them, fell from original righteousness and communion with God, and so became dead in sin, and wholly defiled in all the faculties and parts of soul and body.

They being the root, and by God's appointment standing in the room and stead of all mankind, the guilt of this sin was imputed, and corrupted nature conveyed to all their posterity descending from them by ordinary generation.

From this original corruption, whereby we are utterly indisposed, disabled and made opposite to all good, and wholly inclined to all evil, do proceed all actual transgressions.

This corruption of nature during this life, doth remain in those that are regenerated; and although it be through Christ pardoned and mortified, yet both itself and all the motions thereof are truly and properly sin.

Every sin, both original and actual, being a transgression of the righteous law of God, and contrary thereunto, doth in its own nature bring guilt upon the sinner, whereby he is bound over to the wrath of God, and curse of the law, and so made subject to death, with all miseries, spiritual, temporal and eternal.

The Savoy Declaration Chapter VI

III - The Gospel Standard Strict Baptists

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'Our roots go right back to the 1630s in Charles I’s England when the first Particular Baptist church was formed. This has usually been accepted as in London in 1633. By “Particular Baptist” is meant adhering to the Calvinistic doctrines of free and sovereign grace, “particular” referring to the extent of the atonement.' Gospel Standard.org

Articles of Faith

ARTICLE 4 ..THE FALL OF MAN..

We believe in the Fall of our first parents, and that by it the whole of the human race became involved in, and guilty of, Original Sin; and that as they are born into the world, the whole of their posterity are, in consequence, actual transgressors against God . And we believe that by the Fall all men were rendered both unable and unwilling spiritually to believe in, seek after, or love God until called and regenerated by the Holy Ghost .

Scripture references:Rom. 5. 12-21; Ps. 58. 3. 1 Gen. 6. 5; Gen. 8. 21; Job 14. 4; Job 25. 4; Ps. 51. 5; 2 Jer. 13. 23; Jer. 17. 9; Matt. 15. 19; Rom. 3. 10-24; Rom. 5. 12-19; 1 Cor. 15. 22, 45-50; Eph. 2. 3; 1 John 5. 19.

The Gospel Standard Articles of Faith (Gospel Standard Org)

IV - The Thirty Nine Articles of the Church of England

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The problem with quoting from the Thirty Nine Articles (as a frame of reference) is stated in the links : that they seem no longer to be strictly adhered to in the midst of a wide spectrum of views held within the broad scope of the global Anglican Communion. However no other succinct statement has yet been made.

9. " Original " Sin

Original Sin involves more than just following Adam's example. It is an inherited inclination towards wrong, producing inner conflict and incurring God's condemnation. Those who have received new life still retain this sinful tendency, which affects every aspect of their personality and draws them away from obedience to God. This inclination remains sinful, although forgiven to those who believe and are baptized.

Church Society - The Thirty Nine Articles - Article 9 - 'Original Sin'