There are two different hermeneutical principles between the views of the fallen and unfallen humanity of Christ. Scholars who deny Christ's assumption of corrupted human nature emphasise that, due to a fallen humanity, Christ would have inevitably committed sin in the context of the original sin. However, theologians who are in favour of Christ's fallen humanity explain the issue in the person and work of Christ himself. Here, I present John Calvin's biblical views on the body of Christ as the vicarious humanity for all of us. With regard to the biblical truth that the Word became flesh without ceasing to be the eternal of God, Calvin describes the paradoxical character of the event in scripture. Although Calvin never supports the fallen nature of Christ at a literal level, he is inclined to accept the view of Christ's fallen nature at the level of interpretation, because Calvin has no hesitation in saying that Christ assumed a mortal body like us. Calvin is in line with the views of Christ's fallen human nature, for he uses the biblical concept of Christ's mortal body and the principle of sanctification in his own body through the Holy Spirit, except in that Calvin denies Christ's assumption of the sinful nature of Adam after the Fall. Calvin's opinions not only provide us with the common biblical ground with which the two theological camps would agree, but also demonstrate that Christ assumed fallen humanity for us. In this article, I will explain how the view of Christ's unfallen humanity has logical errors and how it distorts the integrity of the Gospel. Next, in order to demonstrate how Christ's assumption of fallen humanity accords with the orthodox faith in Reformed theology, I examine Calvin's biblical arguments of Christ's assumption of our true humanity. Then, I explain that without assumption of our mortal body by Christ there is no vicarious humanity of Christ in Calvin's christology. Particularly, in order to understand the original and biblical arguments for the humanity of Christ, I will use a dialectical approach to both the Institutes of Christian Religion (1559) and Calvin's commentaries, as the best way to grasp the essence of Calvin's theology.