Because He Lives! We have received the victory and eternal life, through Christ death and resurrection.
John 11:25 -- Jesus says... "I am the resurrection and the life. He who believes in Me, though he may die, he shall live. And whoever lives and believes in Me shall never die. Do you believe this?"

1 Corinthians 15:55-57 -- Where death is your victory? Where death is your sting? The sting of death is sin, and the power of sin is in the law. But thanks be to God! Who gives us the victory through our Lord Jesus Christ.