More profundity from Schmemann:

Christianity is above all the belief that Christ did not remain in the grave, that the light of life erupted out of death, and that in Christ’s resurrection the absolute, all-encompassing and uncompromising law of mortality and death has been torn apart and overthrown from within.

As an Orthodox theologian, he not surprisingly lacks the necessary emphasis on the atonement. I would say Christianity is above all both that Christ died for our sins and that he defeated death. But Schmemann is always worth reading.