Z look at what RWP VWS & JFB have said. We all sin but nowhere do they say what you need them to say, that we all sinned in Adam.
I am not disputing that all men sin but you have still not dealt with the infant or mentally handy capped problem.
God is just, would a loving God judge people for something that have not done or are incapable of understanding.
Rom 5:13 (For until the law sin was in the world, but sin is not imputed when there is no law.
Rom 5:14 Nevertheless death reigned from Adam to Moses, even over those who had not sinned according to the likeness of the transgression of Adam, who is a type of Him who was to come.
Infants and the mentally handy capped do not have sin inputted to them as they cannot know or understand the law.
Isa 7:16 "For before the Child shall know to refuse the evil and choose the good, the land that you dread will be forsaken by both her kings.
As is the norm for many of the calvinists on here you will pick a verse that you think supports your view and ignore everything that shows you are wrong in your assumption.