Before Adam’s fall it was not necessary for him to have Christ, because he was righteous and without sin, just as the angels have no need of Christ. If Adam had not fallen, it would not have been necessary for Christ to become our Redeemer.
…The argument is true that eternal life is in the given to him who keeps the law without Christ, because whoever keeps the law is righteous. Adam would have entered into the kingdom of heaven without Christ, if he had not fallen.
…The conclusion is that Adam alone kept the commandments of God before the Fall, but after the Fall and no one has truly been found who has fulfilled the law
—Martin Luther, Disputatio de iustificatione, (1536) in Luther’s Works, 26.185, 187