Our Faith Hinges on Christ - 1 Corinthians 15:14

If Christ be not risen, then is our preaching vain, and your faith is also vain.

Here, Paul is asserting the error of those who do not believe in the literal resurrection. The point is that if Christ is not resurrected, then the whole plan must have been frustrated. In order to perform the resurrection, He had to descend below all things, experience all pain, sorrow, suffering, joy and misery that He could understand them and overcome them all. In this way He was able to triumph over death on behalf of us all. If He did not do this, He could not have all mercy and grace; Thus He could not be a light unto the world and real faith would have been impossible. But because of His ultimate triumph, our faith can rest in Him. His supernal grace and mercy is infinite, and so we can rely on Him to guide and save us.