John 15:13 Greater love hath no man than this, that a man lay down his life for his friends.
Such acts of self sacrice, of laying one's life down for one's friends, are considered noble acts of heroism, an example of which is the sacrifice of the four chaplains of the US Navy, who gave up their lives when their ship was sinking, all life boats filled and all life belts handed out. Having done all they could to save their fellow navy men, they placed their arms around each other, and prayed, and sang hymns, as they went down to their deaths in the sinking ship. When the last jacket had been handed out, the chaplains removed their own and gave them away. As the Dorchester slipped beneath the waves, the four men stood hands linked, their heads bowed in prayer. Their heroid death is commemorated on February 3 each year, and you can read about this act of heroism in the article No Greater Sacrifice,
Jesus went far beyond this. He did for us while were yet unrepentant sinners, enemies of God,
Romans 5:6 ... Christ died for the ungodly.
7 For scarcely for a righteous man will one die: yet peradventure for a good man some would even dare to die.
8 But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us.
9 Much more then, being now justified by his blood, we shall be saved from wrath through him.
10 For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life.