In another context grace can be merited:
1 Peter 5:5
Yea, all of you be subject one to another, and be clothed with humility: for
God resisteth the proud, and giveth grace to the humble.
Here Peter tells Christians
IF THEY WILL HUMBLE THEMSELVES God will give them "grace" or "favor".
By humbling ones self they can merit "grace" with God.
The Greek word "charis" which is translated as grace is the root word for "charisma" as in the "gifts" of the Holy Spirit. So grace is God manifesting himself in FAVOR to his people.
Nowhere does scripture teach that grace means God will overlook the unrepented sins of a Christian.