The sins that cry to heaven for vengeance are as follows: 

Willful murder.

The sins of Sodom.

Oppression of the poor.

Defrauding labourers of their wages.

 

Willful Murder

This is the intentional killing of an innocent person. In the book of Genesis 4:8, Cain turned on and killed his innocent brother Abel. In chapter 4:10, God warned Cain that “your brother’s blood is crying out to me from the ground like a voice calling for revenge”.

The willful killing also includes procured abortion, which is the deliberate and direct killing of a human being in the initial phase of his or her existence, between conception and birth.

Also in this group is negative eugenics, proposed to eliminate the undesirable characteristics of the human species, thereby setting up a roadblock to children seen as abnormal, which amounts to a rejection of children as gifts from God. There is also euthanasia, or what science calls painless killing or easy death or mercy killing. 

In the Gospel of Matthew 2:16, when King Herod realized that the visitors from the east had tricked him, he was furious and gave an order that all the boys in Bethlehem and the neighbourhood who were two years old and younger be killed.

Although the Church today recognises them as holy innocents, their blood is crying to God for vengeance against Herod. Their feast day is celebrated on the 28th of December.