Those who disobeyed the Old Testament law were killed without mercy. It will be much worse for those who displease Jesus. 10:28-29

"Abraham ... offered up Isaac ... his only begotten son."

(And this was a good thing? How messed up is that?) 11:17

The Israelites kept the passover and sprinkled blood on doorposts so that God wouldn't kill their firstborn children (like he did the Egyptians in Exodus 12:29). 11:28

"What son is he whom the father chasteneth not?"
What kind of father doesn't beat his sons now and then? 12:7