"O Lord, you are so good, so ready to forgive, so full of unfailing love for all who ask for your help." Psalm 86:5
The promise to forgive is conditional. You have to have a humble heart to find forgiveness. You have to be brokenhearted over your sin to really repent and turn away from it. However, call out to God with a contrite heart seeking forgiveness and you will be forgiven. It does not matter what the sin was. Your sin will be forgotten like it never happened with God.
This promise is recorded from a prayer written by David. He was thanking God for being who He is. God always showed up in his time of need or distress. God always forgave him and made him more abundant for his repentance. God's forgiveness is mercy experienced through true love. It is a gift that only God can provide and it is available to everyone who is willing to accept it.
The conditions to the promise of forgiveness start with Jesus. You have to accept the gift of salvation that comes only through Jesus. Your faith and love for Jesus allows you to be forgiven in every area of your life. The moment of salvation erases all your past sins for your entire life up to this point. Just because you are a Christians does not mean you don't live in the fallen world or influenced by it. You will never lose your salvation, but you do need to maintain repentance and forgiveness to stay close to God.
God offers forgiveness to everyone. It is equal and fair. The only way you do not get it is if you do not accept it. His forgiveness reveals His love for you. It reveals God's compassion, graciousness, long suffering, mercy, and truth. Pray for to God for forgiveness as an appeal for His kindness. His character is loyal, so you can believe that you will receive it. His redemption is abundant. It is available to you.
Psalm 86:5, 130:7-8, 145:9. & Joel 2:13