You are so correct, in the OT times God was very “hard”.
Question is, why, if God’s a loving God?
Answer; because,
“the law came in through Moses and Grace and truth came in through Christ Jesus”
Let me explain; because “the law came in through Moses.” Meaning what sin was, and the consequences of sin. Also what righteousness was, and the blessing that would follow righteousness. For all “evil” was to be done away with, nothing sparing.
But “Praise be in God” a New Covenant has been established by God. Which was brought in by Christ Jesus. For we also read “but Grace and truth came by Christ Jesus” Now the law is “he that is without sin can throw the first stone” meaning that the law is still active, but only He that is sinless can administer the punishment of it. So the command is “go and sin no more” meaning “stop your sinning” For there is a consequence of sinning and a person “will” be held accountable.
Yes it it very “human” to hate those that hurt you. Very human not forgive, to want revenge, to hold a grudge. To do what is “right in ones own eyes.” But God says to “forgive him that does evil toward you.” So what’s a man to do? Do what is “right in their eyes” or do what is “right in Gods eyes?”
Much love in Christ, Not me