Most probably, Abraham would not have sinned if he had killed Isaac because he was carrying out God’s command. All people have sinned against God (Romans 3:23) and are therefore worthy of death (Romans 6:23). Isaac was a sinner and was deserving of death the same as us all. Therefore, if Abraham had killed Isaac, he would have been carrying out God’s command to execute Isaac, which would have been according to the law of God in which all sinners deserve to die (Genesis 2:17; Romans 6:23).