Heidelberg Catechism, Lord’s Day 51
[Praying for forgiveness of sins is a powerful, liberating thing to do, even when you know—especially when you know!—that God will say yes. That's one of the most striking aspects of the Lord's Prayer, I think: the fact that it is full of petitions that God has promised to answer (the hallowing of his name, the coming of his kingdom, the provision of bread, the forgiveness of sins, and so on). I find it beautiful that Jesus gave us a prayer filled with things for which we can ask with absolute confidence, rather than a list of requests that he might or might not honour. So we can pray: "Becaue of Christ's blood, do not hold against us any of the sins we do or the evil that constantly clings to us." And we can pray it in certainty and confidence that he will say: "Glad you asked."]
Q126. What does the fifth petition mean?
A126. “Forgive us our debts,
as we also have forgiven our debtors” means:
Because of Christ’s blood,
do not hold against us, poor sinners that we are,
any of the sins we do
or the evil that constantly clings to us.
Forgive us just as we are fully determined,
as evidence of your grace in us,
to forgive our neighbours.