God’s forgiveness means this: nothing we do can make him love us less or love us more. His forgiveness is not based on who we are but on who he is.

For as high as the heavens are above the earth, so great is his faithful love toward those who fear him. As far as the east is from the west, so far has he removed our transgressions from us. As a father has compassion on his children, so the LORD has compassion on those who fear him. For he knows what we are made of, remembering that we are dust.

Psalm 103:11-14

Here’s a prayer for the assurance of forgiveness from The Book of Common Prayer. As it happens, it’s a prayer God always answers.

“Grant to your faithful people, merciful Lord, pardon and peace; that we may be cleansed from all our sins, and serve you with a quiet mind; through Jesus Christ our Lord. Amen.”