Why does God punish everyone for the mistakes of two people. How is that fair?

The story of Adam & Eve provides insight into how we humans came to find ourselves struggling with right vs. wrong, with the world in a fallen state full of temptations. The actions of the first humans had lasting consequences for all of us, because spiritual traits are inherited as well as physical traits.

Saying that God is “punishing us” is not the best way to express this. His initial plan for us had nothing to do with sin, or in turn, suffering and death. Because of his love for us, he freely gives all of us the choice to do right vs. wrong, to come to him or to go it alone. Because of the sin of our parents, we inherit the nature to sin as well. This is not due to God’s punishment, but is due to the unfortunate flip side of the nature of love itself.

Luckily, God had a “Plan B” – he sent his son in the the person of Jesus of Nazareth to atone for our sins, and through his sacrifice, restore the universe to its proper order. This has been fully accomplished, but through His divine will, has permitted the world to continue for a while longer, to allow eternal life to those that accept this sacrificial gift.