First, I’ll start with a passage that makes it clear that it’s good for Christians to make moral judgments when people do evil things.
1 And the Lord sent Nathan to David. He came to him and said to him,“There were two men in a certain city, the one rich and the other poor.
2 The rich man had very many flocks and herds,
3 but the poor man had nothing but one little ewe lamb, which he had bought. And he brought it up, and it grew up with him and with his children. It used to eat of his morsel and drink from his cup and lie in his arms, and it was like a daughter to him.
4 Now there came a traveler to the rich man, and he was unwilling to take one of his own flock or herd to prepare for the guest who had come to him, but he took the poor man’s lamb and prepared it for the man who had come to him.”
5 Then David’s anger was greatly kindled against the man, and he said to Nathan,“As the Lord lives, the man who has done this deserves to die,
6 and he shall restore the lamb fourfold, because he did this thing, and because he had no pity.”
7 Nathan said to David, “You are the man! Thus says the Lord, the God of Israel, ‘I anointed you king over Israel, and I delivered you out of the hand of Saul.
8 And I gave you your master’s house and your master’s wives into your arms and gave you the house of Israel and of Judah. And if this were too little, I would add to you as much more.
9 Why have you despised the word of the Lord, to do what is evil in his sight? You have struck down Uriah the Hittite with the sword and have taken his wife to be your wife and have killed him with the sword of the Ammonites.
10 Now therefore the sword shall never depart from your house, because you have despised me and have taken the wife of Uriah the Hittite to be your wife.’
11 Thus says the Lord, ‘Behold, I will raise up evil against you out of your own house. And I will take your wives before your eyes and give them to your neighbor, and he shall lie with your wives in the sight of this sun.
12 For you did it secretly, but I will do this thing before all Israel and before the sun.’”
So, in this case Uriah had done his best to help David to achieve David’s goals, even going so far as to fight for him against his enemies. And how did David repay him? David repaid him by orchestrating his death and stealing his wife. Uriah only had the one wife, and David had lots of wives. But that didn’t stop David from going after Uriah’s one wife – he just would not be satisfied. How did Nathan respond to this? Nathan went to David and made a moral judgment (verbal) against David. David responded well and said he was sorry. But that didn’t get him out of punishment. A bit later in the book, David shows that he really is sorry for what he did. He doesn’t try to get into a discussion about it with Nathan do determine whether he did something wrong to Uriah – he knows that he has done wrong. Although he got his forgiveness in exchange for his repentance, he still got hammered by God for what he did to Uriah. I guess God would have hammered him even more had he not repented at all, though.
Second passage, this one about being grateful. If someone you know has helped you out, then you should let the good thing they have done for you change your character – change the way that you treat others.
21 Then Peter came up and said to him, “Lord, how often will my brother sin against me, and I forgive him? As many as seven times?”
22 Jesus said to him, “I do not say to you seven times, but seventy-seven times.
23 “Therefore the kingdom of heaven may be compared to a king who wished to settle accounts with his servants.
24 When he began to settle, one was brought to him who owed him ten thousand talents.
25 And since he could not pay, his master ordered him to be sold, with his wife and children and all that he had, and payment to be made.
26 So the servant fell on his knees, imploring him, ‘Have patience with me, and I will pay you everything.’
27 And out of pity for him, the master of that servant released him and forgave him the debt.
28 But when that same servant went out, he found one of his fellow servants who owed him a hundred denarii, and seizing him, he began to choke him, saying, ‘Pay what you owe.’
29 So his fellow servant fell down and pleaded with him, ‘Have patience with me, and I will pay you.’
30 He refused and went and put him in prison until he should pay the debt.
31 When his fellow servants saw what had taken place, they were greatly distressed, and they went and reported to their master all that had taken place.
32 Then his master summoned him and said to him, ‘You wicked servant! I forgave you all that debt because you pleaded with me.
33 And should not you have had mercy on your fellow servant, as I had mercy on you?’
34 And in anger his master delivered him to the jailers, until he should pay all his debt.
35 So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart.”
What is really bad is when you treat someone well by performing X for them… assisting them financially, helping them to find a mate, helping them to achieve success, getting them a job, giving them gifts, serving them somehow, etc. and then they come back and actually undermine you in the exact same area where you helped them. That’s the really bad situation that you want to avoid. If someone helps you by doing X, make sure that you don’t turn around and hurt them by doing (not X) back to them – hurting them in the very area where they tried to help you.
I’m going to try to tie these two passages together. Imagine how this ingratitude would work in the David and Uriah case. Suppose Uriah helped David somehow to try to win the heart of a woman he really liked. Then David turns around and steals Uriah’s wife in response to being helped. You don’t want to be that guy who responds to kindness by doing the exact opposite of how you were helped. I think it’s important to respect the abilities of the people who help you and let the gratitude you should feel for them change your character. Don’t respond to them by doing the exact opposite for them or others that they did for you. And if you see someone doing that, give them the Nathan treatment – “you are the man!”. Awesome. Don’t be the guy who won’t make a moral judgment because he wants to be friends with David, even over the dead body of Uriah.