"And yet not only does your religion say that all humans deserve death, but it also says that in the future God will destroy this planet with fire so that he can create a new one. That sounds remarkably close to what you're saying you no longer believe."
Yes we do deserve death, because we've sinned against a holy and just God every, single, day.
And the things we've broken are not minor oversights. Have you ever lied before, taken anything without asking, looked upon the other with lust in your heart or hated someone in your heart? Have you taken God's name in vain?
When you've broken all of these, then what are you? A liar (Exodus 20:16), a thief (Exodus 20:15), an adulderer/adulteress (Matthew 5:27-28), a murderer (Matthew 5:21-22), and a blasphemer (Exodus 20:7).
Those are only 5 of the 10 commandments you and I have broken. We have not just sinned against each other by the said sins, but we've sinned against God; and because of that He is well within His rights - as a creator - to destroy all of us. But He does not.
We do not deserve life or any good that may come but only bad, and yet have given us good anyways (Matthew 5:45).
And has given His only Son, to die for us so that we can escape His coming judgment upon the world (John 3:16-17).