"Be merciful, even as your Father is merciful." -Luke 6:36
How is God our heavenly Father merciful? In that he gives us all things, natural and spiritual, temporal and eternal, gratuitously and out of pure goodness. For should he give to us out of and according to our merits, he would have to give us only hell-fire and eternal condemnation. Therefore what he gives us in our possessions and honor, is given out of pure mercy. He sees that we are captives of death; but he is merciful and gives us life. He sees that we are the children of hell; but he is merciful and gives us heaven. He sees that we are poor, naked and exposed, hungry and thirsty; but he is merciful, and clothes, feeds and gives us to drink, and satisfies us with all good things. Thus, whatever we have for the body or spirit, he gives us out of mercy, and pours his blessings over us and into us. Therefore Christ says here: Imitate your Father and be also merciful, as he is merciful.
Now this is not a common mercy, nor one that reason teaches. For that is selfish: it gives to the great and learned and those who merit it; loves those, who are beautiful; gives to those from whom it has some benefit or advantage. That is a political, beggarly, shaggy, piece-meal mercy. For if I give to him, who merited it, or if I regard beauty and friendship, then it is duty and debt and not mercy. This is also what the Lord meant, when just before in Luke 6:32-34 saying:
“If you love those who love you, what benefit is that to you? For even sinners love those who love them. And if you do good to those who do good to you, what benefit is that to you? For even sinners do the same. And if you lend to those from whom you expect to receive, what credit is that to you? Even sinners lend to sinners, to get back the same amount."
However, Christian mercy should not seek its own. It must be round, and open its eyes and look at all alike, friend and foe, as our heavenly Father does. And where this mercy is not, there is also no faith. For if your heart is in the state of faith that you know your God has revealed himself to you to be so good and merciful, without thy merit, and purely gratuitously, while 83 you were still his enemy and a child of eternal wrath; if you believe this, you cannot refrain from showing yourself so to your neighbor; and do all out of love to God and for the welfare of your neighbor. Therefore, see to it that you make no distinction between friend and foe, the worthy and the unworthy; for you see that all who were here mentioned, have merited from us something different than that we should love and do them good.
"But love your enemies, and do good, and lend, expecting nothing in return, and your reward will be great, and you will be sons of the Most High, for he is kind to the ungrateful and the evil." -Luke 6:35
[This is an excerpt from a sermon preached by Martin Luther]