We are debtors to the justice of God. Our debts are our sins. We have transgressed his law thousands and thousands of times and his justice demands punishment in Hell.
Not All
Go does not forgive all the sins of all men. Some men and women are condemned for ever. There will be those to whom Christ shall say, "Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels", Matthew 25:41. Only those who, while in this world, are brought to faith in Jesus Christ are forgiven and go to Heaven when they die. Christ has borne the punishment of their sins on the cross. "And thou shalt call his name JESUS : for he shall save his people from their sins", Matthew 1:21.
Forgiven and Forgiving
"As we forgive our debtors", does not describe the basis of God's forgiveness. Forgiving others does not earn forgiveness from God. It is, however, a characteristic of those who are forgiven for Christ's sake, that they do forgive others, Ephesians 4:32, Matthew 18:23-35. Every forgiven man is a changed man. And part of that change is a willingness to forgive.
This forgiveness has nothing to do with setting aside civil punishment where crime has been committed or neglecting church discipline where it should be exercised. It means not wishing ill toward another because they have done wrong to us, though we should care about the dishonour done to God. Where there is acknowledgement of wrong and desire for forgiveness it should be freely given.
Do you forgive others? Are you forgiven by God? Is Christ your saviour? Can you say of Christ with the Apostle Paul "In whom we have redemption through his blood, the forgiveness of sins, according to the riches of his grace", Ephesians 1:7?