Again, I can only give an outline of my own thinking on this.
Does God punish millions of people because two people decided to disobey him? Those who take the Bible very literally would say yes, and they are entitled to their view of faith, but that is not my view at all, nor is it the view of many other Christians.
Imagine a timeline of let's say 100 billion years. What fraction of that is our lifetime - say 70 years? Of those 70 years, say people have on average an appalling time for maybe only a part of it, fpr convenience say 10 years. What fraction/percentage of that 100 billion years is 10 years?
If my maths is any good, that means you get to suffer for one hundred thousandth of your life, and you get the other 99,999,990 years of peace to make up for it.
Why the suffering? Perhaps...just perhaps to see what we make of it. And to give us some perspective on what suffering actually is. Otherwise if everything was perfect always, how would you know it was? We can only see things by comparison to something else. With nothing else to compare it to, how would we? With nothing to test our views of things, how would God know if we could make good decisions?
I'm not saying I'm right, but this is how I reason that God has a perfectly valid way of doing things. It might seem unfair at the time, but even whilst I've had some appalling years, God's still been there to give me the strength to get through the bad times. I can't find a reason to complain about him at all.
As I said beforehand, what would be the deal if there was no God? 70 years including the years that are awful, then you die.
Is that a better deal?
If so, how?