I wonder whether there is scope for this view of this novel through analysing what the novel has to say about the human condition and how Robinson Crusoe struggles to return to civilisation. What is interesting about the story and in particular the character of Robinson Crusoe is that when he finds himself on this island, he embarks on a struggle to remain a civilised man and maintain his reason. The novel says his "original sin" was his refusal of a normal life where God had placed him. In particular, the story states that he was not "satisfied with the station wherein God and Nature hath placed" him. He is therefore placed in a setting where he will have to struggle to remain human and civilised and good. Allegorically, we could read this as a struggle between good and evil. He is tempted at various stages to become less civilised and to reject reason, which could be viewed as slipping into evil ways.
However, the way in which Crusoe triumphs over the forces that are ranged against him shows how clinging on to our civilised and good status as human beings can help us to overcome the struggles that we face that tempt us to become evil. Therefore it might be possible to view the theme of the human condition as being something we could use to think about whether this text is a Christian allegory.