1 Corinthians 15:13

But if there be no resurrection of the dead, then is Christ not risen. Not only because Christ was one of the dead, but also because the primary cause of Christ's death and resurrection was the complete destruction of death, and the restoration of life. Moreover, the resurrection of Christ was a pattern of ours, i.e., of our resurrection to righteousness in this life, and to glory in the next. See S. Thomas (p. 3, qu. 53, art. 1) for five other reasons why it was necessary for Christ to rise again.