you will no longer be called Jacob; your name will be Israel.” So he named him Israel

 Genesis 34-35

Because their sister Dinah had been defiled, Jacob’s sons replied deceitfully as they spoke to Shechem and his father Hamor. They said to them, “We can’t do such a thing; we can’t give our sister to a man who is not circumcised. That would be a disgrace to us. We will enter into an agreement with you on one condition only: that you become like us by circumcising all your males. Then we will give you our daughters and take your daughters for ourselves. We’ll settle among you and become one people with you. But if you will not agree to be circumcised, we’ll take our sister and go.”

Three days later, while all of them were still in pain, two of Jacob’s sons, Simeon and Levi, Dinah’s brothers, took their swords and attacked the unsuspecting city, killing every male. They put Hamor and his son Shechem to the sword and took Dinah from Shechem’s house and left. The sons of Jacob came upon the dead bodies and looted the city where their sister had been defiled. They seized their flocks and herds and donkeys and everything else of theirs in the city and out in the fields. They carried off all their wealth and all their women and children, taking as plunder everything in the houses.

After Jacob returned from Paddan Aram, God appeared to him again and blessed him. God said to him, “Your name is Jacob, but you will no longer be called Jacob; your name will be Israel.” So he named him Israel.

Why?

Sons of Jacob did what they thought was good. By track, they killed people of Chechem to pay back for their sister Dinah, who was defiled.

Circumcision is a symbol of cleanliness.

How?

Do evil may welcome the revenge or disaster.