grace is typically defined as unmerited favor. To put it into plain English, grace is when God saves someone despite them not doing anything to earn that salvation. In fact, they may be doing everything to not earn salvation. So, grace could be defined as God's continual love for mankind despite their (or our) best efforts! In the Bible, God set up a rule: if you eat of the tree of knowledge of good and evil, you will die that same day (Genesis 2:16-17). This was not a one-time command, but it is true for everyone of us. Whenever we reach out and take that which we shouldn't, we earn death (Romans 6:23). So, God steps in, and offers life as a gift at no cost to us. Grace, then, could be defined as God breaking or overruling His own rules.
One example of this is found in Jeremiah 3:
Then the LORD said to me in the days of Josiah the king, “Have you seen what faithless Israel did? She went up on every high hill and under every green tree, and she was a harlot there. 7 “I thought, ‘After she has done all these things she will return to Me'; but she did not return, and her treacherous sister Judah saw it. 8 “And I saw that for all the adulteries of faithless Israel, I had sent her away and given her a writ of divorce, yet her treacherous sister Judah did not fear; but she went and was a harlot also. 9 “Because of the lightness of her harlotry, she polluted the land and committed adultery with stones and trees. 10 “Yet in spite of all this her treacherous sister Judah did not return to Me with all her heart, but rather in deception,” declares the LORD.Jeremiah 3:6-10
Under the law, if someone was divorced and they went and married another, they could not return to the original husband because “she has been defiled” and “that is an abomination before the Lord” (Deuteronomy 24:1-4). In Jeremiah 3, we learn that this is exact situation had happened with God, Israel, and Judah. Yet, what does God promise?
Go and proclaim these words toward the north and say, ‘Return, faithless Israel,' declares the LORD; ‘I will not look upon you in anger. For I am gracious,' declares the LORD; ‘I will not be angry forever.Jeremiah 3:12