What is THE MOST Important Thing?

"I passed on to you what was most important and what had also been passed on to me--that Christ died for our sins, just as the Scripture said, He was buried, and he was raised from the dead on the third day, as the Scriptures said. He was seen by Peter and then by the twelve apostles. After that, he was seen by more than five hundred of his followers at one time, most of whom are still alive, though some have died by now. Then he was seen by James and later by all the apostles. Last of all, I saw him, too, long after the others, as though I had been born at the wrong time." - 1 Corinthians 15:3-9