Well, let's say, for the sake of argument, that Christ never did rise, and That he was simply a man who, as protestant liberals might say, was simply a wise and moral teacher.Then the truth of the matter would be that the entirety of the faith would be in jeopardy of being nothing more than simply an ethical philosophy (that is, after what one could parse out of the mythical/religious context), and it in itself, ironically enough, would have an existential dilemma. Without the resurrection, without the supernatural impeding the natural in the manner that it is presented in the Christian schema, the faith has no validity as anything but an opinion on the life lived in mortality.
It wouldn't really matter if I, or anyone, accepted Christ's teachings as anything but a vain attempt at ethically ordering one's life. Without the resurrection, there is no telos in the existential system, there is no reason why one should do anything for the sake of morals or ethics or even human progress. Without the resurrection, there is no point to anything, and we should all continue our lives in the base attempt at satisfying our animal craving for orgies, libation, and gluttonous eating. And, I know that a liberal theologian would want to say that something like Humanism or the human's ability to transform and take charge of their own ethical leanings is the next evolutionary step on our process toward whatever teleological end they might dream up, but the truth is, if there is no resurrection, and the God that reigns is the God of the deist, then...well, truthfully... there is no progress, and if God doesn't care, then why should I? why should you?
But, if the resurrection is real, if it is something that occurred historically, if it is something that is actively changing and shaping my life and the life of every other believer, then the stakes have changed. The picture becomes not one of a person chasing the ends of human ethical limitations but one of her being honed and shaped and molded by the God of the universe to be more like Him - to be ever more perfectly what He made her to be.
If the resurrection is real, then I know that it is not by my own power or morality but by the very hand that created the seas that I am being transformed, and I can be confident, as Paul assures us, that He will be faithful to complete this amazing teleological work in me. If the resurrection did occur, then I know that Christ sits at the right hand of authority, and I know that there really is a point to following Christ and that, as Romans 8 relates, there really is freedom from the condemnation that we were once under by the sacrifice and resurrection of the Son of God.
Without the resurrection, Christianity is nonsensical; without the resurrection, pun intended, Christianity is dead.