Therefore, my dear brothers and sisters, stand firm. Let nothing move you. Always give yourselves fully to the work of the Lord, because you know that your labor in the Lord is not in vain. -1 Corinthians 15:58
WHAT IS THE GOSPEL? Well 1 Corinthians 15:1b, 3-4 tells us, "I declare unto you the Gospel . . . that Christ died for our sins according to the Scriptures; and that He was buried, and that He rose again the third day according to the Scriptures" - That is what many call "The Gospel in a nutshell".
“The sting of death is sin; and the strength of sin is the law. But thanks be to God, which giveth us the victory through our Lord Jesus Christ.” 1 Corinthians 15:56-57 KJV http://bible.com/1/1co.15.56-57.kjv