I'm also a merciful God. I'm not going to have you kill your son. Another sign of this covenant is in the Old Testament in the Torah that it demands that sons of the Jewish faith are circumcised. You can go Google that if you don't know what it is, but that is supposed to be the flesh sign that I am one of these people that has made this deal with God. Now you have to remember that Abraham, the dude was 75 years old. He didn't have any children. So as part of this deal, he's got to make babies.