If God is all-just, why does he punish/kill massive amounts of people throughout the Bible for the sins of one? Examples: *God murdered 70,000 Israelites by inflictin them with disease because one man, David, conducted a census *God punished Egypt with 10 plagues, which included murdering all male first-born babies because God had a vendetta against Pharaoh [whose heart was hardened by God so that Pharaoh could not release the Israelites even if he wanted to] *God puts all of mankind to death because of Adam’s
Actually if God was all-just he would kill every one on Earth. Justice is a terrible thing. When you drive on a highway 1 mile over the speed limit, according to justice you deserve a speeding ticket. Justice of God would require annihilation of all people as soon as they commit the slightest sin. Lucky for us He is also merciful. And vast majority of times, the mercy of God prevails over justice. For the thousands of people God has punished with death in the Old Testament, there are millions upon millions of really bad people who God is merciful to even though they should be punished.
Secondly, murder would not be the term you would apply to God. He gave life to each person on Earth. And if He gave life, He has the right to take it away at any time. In fact He takes away everyone’s abiliy to continue living on this Earth sooner or later. So when we talk about death punishments in the Old Testament, a more accurate term would be termination of life rather than murder.
There are several cases in the Old Testament where it seems like God punished thousands of people for the sin of one man. And yet, we don’t know how sinful all those other people were. Throughout the history of Israel, these people were constantly rebelling agains God and were quick to follow the sins of other nations. So when David was conducting a non-approved census, those thousands very likely died for their own sins, not because of anything David did.
When all firstborn of Egypt died, it had hardly anything to do with God not liking pharaoh. Remember how just a few years before that Egyptians decided to kill all male children of Israel? And that mass genocide was a national effort, not just pharaoh’s. So it was about justice done for murdering the children of Israel, rather than conduct of pharaoh.
About Adam, the Bible says sin entered into the world through Adam, which means Adam was the first to die because of sin. Everybody who was born after Adam, can’t say they are punished for the sin of Adam, because every one sinned in their lives of their own will. So everyone dies for their own sins really, not for anything Adam did.
The two people in history who never sinned, or at least almost haven't sinned, never saw death, Methuselah and Elijah.
It is very common for people in America today to accuse God of all sorts of injustice. The irony of that is these people have it better than most people on Earth today and throughout history. Perhaps a better approach to life would be to appreciate something good God has done in your life, to be greatful to God for still allowing you to live on this planet, even though you sin against God and other people every day. The attitude of bitterness is a bad way to live. It eats you up alive.