We want them to know who family is because family matters. We want them to understand that Silas’s middle name may be the name of an apostle, but it is also the name of one of his great-great-grandfathers; that Judah’s middle name may be the name of a great prophet, priest, and judge but it is the name of another great-great-grandfather as well. Even if they never knew those men, there is a connection.
Just look at the book of Obadiah. By the time it was written, few, if any, of the Edomites knew the Jews personally, but it still mattered to God that a long time before that Jacob and Esau had been brothers. He expected those two nations to treat each other like brothers.
Because of the violence done to your brother Jacob, shame shall cover you, and you shall be cut off forever. On the day that you stood aloof, on the day that strangers carried off his wealth and foreigners entered his gates and cast lots for Jerusalem, you were like one of them. But do not gloat over the day of your brother in the day of his misfortune; do not rejoice over the people of Judah in the day of their ruin; do not boast in the day of distress. Do not enter the gate of my people in the day of their calamity; do not gloat over his disaster in the day of his calamity; do not loot his wealth in the day of his calamity. Do not stand at the crossroads to cut off his fugitives; do not hand over his survivors in the day of distress. Obadiah 1:10-14.
Because they did not help, because they “gloated” over their brothers’ misfortune, because they actively stood in the way to prevent escape, God judged the Edomites and destroyed them. Their relationship with Israel was many generations removed, their people’s knowledge of one another socially was small if at all, yet they were still expected to act like brothers.
So what does God think about siblings who argue over estates? About grudges that are held for decades? About bad feelings that are passed down to the next generation instead of being hid out of shame that such a thing exists in their hearts? God expects better of families, and why? Because that is the model for His people, the church.
The church is often described as “the household (family) of God,” and that makes us brothers and sisters. God expects us to act like flesh and blood brothers and sisters. He expects us to love one another, not because we know one another, but because we are spiritually related—family. He expects us to forgive, to forbear, to help, to encourage and yes, even to admonish just as an older brother or sister would a younger one. It does not matter whether we “know” one another or not.
Let’s add this quickly because someone is thinking it—yes, God even expects us to put His spiritual family ahead of our physical families; but assuming that is not an issue, my family life, even with the most distant of relatives, had better be a good one. How else will I know how to treat my brothers and sisters in Christ?
Do not rebuke an older man but encourage him as you would a father, younger men as brothers, older women as mothers, younger women as sisters, in all purity. 1Tim 5:1-2