So even though there is not a single verse that says "forgiveness is a gift".
And there are several verses that say we will be forgiven as we forgive others... Matt 6:12; Matt 6:14;
Mark 11:25; etc...
And there are several verses that say if we do NOT forgive others, we will not be forgiven... Matt 6:15;
Matt 18:35; Mark 11:26; etc...
And several more verses that say we have to repent in order for forgiveness... Acts 2:38; Acts 5:31; Luke 3:3;
...and finally even though there is scripture that says ... :"If" we confess our sins He will forgive us... ( 1 Jn 1:9; )
You believe forgiveness is an unconditional gift?
If it's not in the Bible, and there are several verses that say just the opposite, it's possible it could be a doctrine of demons.
If we do not repent - we are not forgiven.
If we do not forgive others - we are not forgiven.
If we we do not confess our sins - we are not forgiven.
That doesn't sound like a gift.