The Imputation of Adam’s Sin
Adam's posterity are under a curse. We live in a world of sin and we all die because of his rebellion. Not Fair? Every time you sin you give your "yea and AMEN" to what he did. We have such solidarity with Adam as fallen creatures that he federally represented us - such that what he did, counts as what we did. Likewise the last Adam, Jesus Christ, federally represents us so that what he did for us also counts as what we did. You cannot reject this doctrine for Adam but have it for Christ.