Satan understood exactly what God said in Genesis 3:15 when God promised a seed, a son, that would bruise his head, i.e., eliminate him for good. What do you suppose Satan's priority became after hearing God say that? Kill the baby! Satan did his absolute best to make sure the promised seed would never see the light of day. He decided he could do that by killing someone in the bloodline of Jesus, thus preventing Jesus from ever making the scene here on earth. He almost succeeded in the days of Noah when God said,
And GOD saw that the wickedness of man [was] great in the earth, and [that] every imagination of the thoughts of his heart [was] only evil continually. Gen 6:5
Was it God's will for Harod to kill all the babies under 2 years old in an attempt to eliminate the promised seed? Nope. That would have been yet another attempt of many by Satan to keep himself in power over this world. It always amazes me to hear someone say, "God took my baby to be with Him in heaven." The first thing that pops into my mind is that they are really saying, "God
murdered my baby because He is so selfish and wanted another dead baby with Him in heaven." What an absurd thought! I often wonder what people think Satan is doing when God is supposedly killing millions of people in wars and such. Do they think Satan just stands by smiling while God does his dirty work for him?
Given that man had free will (God couldn't just force them to be good), His only option was to eliminate all but Noah who just so happened to be both a righteous man, as well as a man through whom the promised seed would eventually come. It may be more accurate to say that it was men who beat their own head against a rock because they refused to live as God intended. Remember, when God created them His idea was for them to live a perfect live in a perfect setting. It certainly wasn't His idea for them to believe the lies of the devil.
Try to imagine God's dilemma; It wasn't His will to just kill people, but He knew that if He didn't do something eventually Satan would succeed in eliminating someone in the bloodline of Christ, thus eliminating Christ himself. That of course would mean we would still be dead in trespasses and sins, without God and without hope. God's hands were full in trying to keep the bloodline alive. Remember, people have free will. God dealing with Israel might be compared to herding millions of cats to do your will! Not an easy task to say the least, but somehow God managed to work with that herd of cats to get them to do what it took to keep the bloodline alive. True, it wasn't always pretty, but I can't imagine what else God could have done. He begged people to believe His words and was a plain as He could be in telling them what happens to them when they disobey.
Deut 30:19,
I call heaven and earth to record this day against you, [that] I have set before you life and death, blessing and cursing: therefore choose life, that both thou and thy seed may live:
Anyway, eventually God pulled it off, His son came into the world and redeemed mankind from sin and death. But along the way, Jesus also revealed the true will of God, showing that God is love and not evil. Paul explained that it was always God's will for people to be saved and know the truth. Jesus also revealed how the true cause of all evil things was Satan and not his Father, God. Before Jesus opened the eyes of those who believe, it simply was not available for people to grasp the full reality of Satan and his doings, so God simply "took the rap" for all the evil done in the world.
In any case, we, in this age of grace, should now know that God's will if for EVERYBODY to be saved and know the truth. But, as I've said and we must never forget, man has free will, and if he wants to start wars, then so be it. God will do His best to work with man's free will, and He often succeeds in minimizing the damage.
In short, don't blame God for all the stupid decisions man has made throughout history. Hopefully all of this will give you something to think about regarding the apparent difference between the God of the OT and the God Jesus revealed in the NT. God did the best He could to herd the cats, but unfortunately many suffered and died trying to go against God's perfect will. God would have been more than happy for Adam to have simply obey one simple command, and thereby live a life of true righteousness and holiness. It's absolutely amazing that He could have changed pulled off our redemption through his son, who also had free will and was tempted just like the rest of us. Fortunately for us, the man (not some grotesque, pagan god-man construct) Jesus obeyed his Father to the letter, even to a gruesome death on the cross.
Take care...