Now while the sons of Israel were in the wilderness, they found a man gathering wood on the sabbath day. Those who found him gathering wood brought him to Moses and Aaron and to all the congregation; and they put him in custody because it had not been declared what should be done to him. Then the Lord said to Moses, “The man shall surely be put to death; all the congregation shall stone him with stones outside the camp.” So all the congregation brought him outside the camp and stoned him to death with stones, just as the Lord had commanded Moses (Numbers 15:32-36).

Moses interceded for all Israel when God was determined to destroy them for their rebellion against His command to take the Promised Land (cf. Numbers 14:11-19). He also intercedes for his sister Miriam, who was afflicted with Leprosy for challenging Moses' authority (cf. Numbers 12:1-15). But Moses does not intercede for this man, who violatated God's command by gathering wood on the Sabbath. 

Abraham interceded for Sodom when the LORD was determined to destroy it probably because he knew that his nephew Lot was there. Could Moses have been thinking of his loved ones when God was intent on destroying the whole lot of rebellious Israel, which likely included the Levites? Would Moses have interceded for this man, who violated the Sabbath, he was a near relative?

I would like to suggest that perhaps the Patriarchs and Moses practiced selective intercession. They would pray for their own, but they would let the others be condemned. 

Now, I ask a moral question. Is this wrong? Is it wrong for you to care more for your own country than for other countries, your own people more than other peoples? How about your own family over other families, your own child over other children?

I think in every case we would say it is not wrong and perhaps we would also say that it would be wrong to do otherwise. But are not people people? What makes one any different from any other? 

But Christians are different from non-Christians. Even with respect to judgment, the Bible says that they are to be treated differently: 

What business is it of mine to judge those outside the church? Are you not to judge those inside? God will judge those outside. “Expel the wicked person from among you.” (1 Corinthians 5:12-13)

The Bible also warns against being unequally yoked with unbelievers:

Do not be yoked together with unbelievers. For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness? What harmony is there between Christ and Belial? Or what does a believer have in common with an unbeliever? What agreement is there between the temple of God and idols? For we are the temple of the living God (2 Corinthians 6:14-16).

Is it that believers are so much more moral than unbelievers?  Both the Bible and experience reveal that this is not the case. Then, what is the basis of this special treatment of one over another? 

I believe it has to do with identity, whether biological (i.e. by blood ties) or spiritual (i.e. by a common faith). 

If you are simply a member of God's creation, you experience God's common grace, whereby He brings the sun on the evil as well as on the good and the rain on the good as well as the evil (cf. Matthew 5:45).

But if you are His chosen chilld, then you are a "co-heir with Christ." You are forgiven every sin, whether past, present, or future. You have the indwelling Holy Spirit, whereby you are guaranteed an eternal inheritance in heaven.

None of these are available to the unsaved. Yes, God loved the world so as to give the life of His One and Only Son, but this love would be short-lived for all those that reject His Son, for these would all be condemned forever in the Lake of Fire. As the Scripture says, "Light has come into the world, but people loved darkness instead of light because their deeds were evil" (John 3:19).

As mothers naturally care for their own children over every other child, so God cares for His elected children over every other unsaved person. Paul brings this out in the analogy of Jacob and Esau, about whom the Scripture says, "Jacob I loved, Esau I hated" (Romans 9:13; Malachi 1:3).

Therefore, it is not so wrong for us to intercede more for our loved ones than anyone else. However, Jesus does disrupt this order of things by commanding greater and deeper ties be found in one's spiritual identity than in one's biological identity:

If anyone comes to me and does not hate father and mother, wife and children, brothers and sisters—yes, even their own life—such a person cannot be my disciple (Luke 14:26).

He replied to him, “Who is my mother, and who are my brothers?” Pointing to his disciples, he said, “Here are my mother and my brothers. For whoever does the will of my Father in heaven is my brother and sister and mother." (Matthew 12:48-50).

And everyone who has left houses or brothers or sisters or father or mother or wife or children or fields for my sake will receive a hundred times as much and will inherit eternal life (Matthew 19:29).

Friends, it is right to have a deeper love for those biologically tied to us than to others. And as we more fully realize our place in God's family, it is even more right for us to have an even deeper love for those that share our faith in Christ. Biological ties will cease with this life; however, spiritual ties will endure forever.