Their sins were so terrible that they emulated the paganistic traditions of the Canaanites sacrificing their children at the altar of Molech, an idol they worshipped in a place called Tophet in the valley of Hinnom or Gehenna in the Southern part of Jerusalem.
This is how it’s done; they would set fire under Molech and because the idol is made of metal, it will be very hot and it’s at that point they would lay the baby in the hands of Molech and the baby would cry to death.
To prevent the parent of the baby or any sympathizer hearing the agonizing cry of the baby, the worshippers would beat their drums and blow their trumpets, dancing and celebrating.
What a terrible and barbaric act. See how it is done in the pictures in the link below and also read the rest of the message from the link: