Law
God has laws – the 10 commandments. Much like how a country has laws. There’s due punishment for breaking one of those laws.
Accounts
You have an account with God – an account that stores all of the bad deeds (sins) you’ve ever committed. All humans have their account with God.
Jesus is God, but became a human (fully human, fully God) and also had account with God.
Justice
God is a holy and just God – meaning that a bad deed cannot go unpunished. Much like how in the U.S. if you commit a crime, “you do the time.”
The Judgement
Just like when you commit a crime in the U.S., you go before the judge to get your due punishment.
Same way with God. At the end of this present evil age, all will go before God – the judge – to give an account of everything they’ve ever done to break his law, and they will receive due punishment – eternal separation from God in hell.
The Cross – The Switch
In the U.S., if you commit a crime that must be punished, what if you could have someone who hasn’t committed a crime, take that punishment for you? In the U.S., you can’t. You yourself must pay your own penalty.
However, with God, He does allow someone who has never committed a sin against Him to take the punishment for you in your place. There’s only one person that ever lived and will ever live that has a perfectly clean account with God – Jesus!
So what did God do to Jesus on the cross? He opened your account. Took all of your sins and put them on Jesus’ clean account, and punished Jesus on the cross. Now you have a perfectly clean account and when you stand before God – the judge – He’ll open up your account and see a perfectly clean account, and can let you into heaven!
Believe
There’s only one requirement, and it’s dead simple. You must believe that Christ did this for you, and you will be forgiven of all your sins. If you try and bring your own good deeds (works), you will be rejected. Just as in the U.S., if you steal something, you can’t just say, “Well I’ll just give $50 to charity and we’ll call it even.” You must pay the penalty!
And you also can’t take the mark of the beast, or else game over.