Because John Wesley is often called Arminian, we sometimes think he and the Methodists deny that the guilt of Adams sin was imputed against mankind, but this is not the case at all.
Both Calvinists and Methodists adhere to the doctrine of original sin which rests on Adams guilt being imputed against men, so that before we are born we are guilty of sin. From this guilt we are cursed to a sinful nature so that as soon as we have the ability to make moral choices we add out own sin to the original guilt of Adam's sin.
Nowadays people are not aware that this is the basic teaching of all Protestants, so even those who call themselves Calvinists are more Arminian than John Wesley when they discuss this.
For example, John Wesley in arguing for the imputation of guilt said:
"that guilt was imputed to the scapegoat, to the children of wicked parents, and to our blessed Lord himself, without any personal sin." (The Complete Works of JOHN WESLEY, V9, P 369)
Now the people famous for not believing in the imputation of guilt for Adam's sin are the historicaly Pelagius. (Arguably Arminius also, but as some later Arminians later support the imputation of guilt, the waters become murky, more detail can be found at this post.) These are those historic men who denied the imputation of guilt upon Adam's offspring and considered the sinful nature not as a curse for guilt, but a kind of weakness that God allowed to pass onto humanity. Some Arminians thought that God would never judge the innocent, so until a person willfully sins they can't be properly judged. This opposes both Calvinists and Methodists, or at least their founding church fathers, who support the imputation of guilt upon humanity.
To see what a person believes about original sin and imputed guilt, all you have to do is look for their comments of this verse:
Nor can the gift of God be compared with the result of one man’s sin: The judgment followed one sin and brought condemnation, but the gift followed many trespasses and brought justification. (NIV Romans 5:16)
For example here is how Luther asserts imputed guilt on his comments of Rom 5:16.
From which it is clear that original sin is the actual sin of Adam himself, because the apostle says, “Many died through one man’s trespass.” Therefore this one sin of the one man is the sin of all, by which all have died with him. Moreover, original sin is the same as the actual sin itself which Adam sinned, which all his sons bear, and of which they are all guilty. For together with his nature he also transmitted his sin to all men, because just as he himself by a sin of this kind was made a sinner and an evil man, so nothing is born of him except sinners and evil men, that is, men prone to evil, who find it difficult to do good. (Luther's Commentary on Romans)
Calvin argues for imputation of guilt on the same verse:
This is especially an explanation of what he had said before, — that by one offense guilt issued in the condemnation of us all, but that grace, or rather the gratuitous gift, is efficacious to our justification from many offenses. (Calvin's Commentary on Romans)
I could go on and quote hundreds of men who recognize the imputation of guilt cursing all humanity into a depraved sinful nature, prior to birth, but maybe it is best just to leave it with Kind David who said it so well.
Surely I was sinful at birth, sinful from the time my mother conceived me. (Psalms 51:5)
Now the Arminians and Pelagians (as opposed to the Calvinists and the Methodists) have no solid ground to stand on when opposing imputed guilt and condemnation for Adam's sin because if men are born innocent that God was unjust to curse David into sin before he was born.
The reason why it is important for us to learn the doctrine of past generations like this one, is that it is exactly the same way in which Christ's righteousness is imputed to sinners who have not actually committed righteousness. In both cases an imputation of guilt or righteousness occurs without the other person committing it. It might seem weird, even unjust to some, but this has always been the way God has judged men, i.e. under the federal head of either Adam or Christ.
We are either sinners or not based on whether we have been born from Adam or born again in Christ. When we are first born we are born wicked and condemned because we are under the guilt of Adam's sin. When we are born again all the guilt is put on Christ and His perfect obedience imputed to us. The beauty of grace is that in a sense it is not fair and on that account we have much to rejoice over.