367. These things do not need to be proved by similar passages from the Word beyond the identification of charity as the brother of faith and the symbolism of a field as every point of doctrine.
From the nature or essential character of faith, anyone can see that charity is the brother of faith. The brotherhood of these was also represented by Esau and Jacob — another relationship that gave rise to controversy over the birthright and the dominance it entailed. The same brotherhood was represented by Perez and Zerah, Tamar's sons by Judah (Genesis 38:28-29, 30), a story that also dealt with birthrights. And it was represented by Ephraim and Manasseh (Genesis 48:13-14), likewise a tale about birthrights and the implied dominance. The same thing was represented by others, too.
Both faith and charity, after all, are the church's offspring. Faith is called a man, as Cain was in the first verse of this chapter, and charity a brother, as in Isaiah 19:2; Jeremiah 13:14; 1 and elsewhere. The union of faith and charity is called a brothers' pact in Amos 1:9.
 Something like the relationship symbolized by Cain and Abel was represented by Jacob and Esau, as I said, in that Jacob wanted to supplant Esau. This can be seen in Hosea too:
... to bring on Jacob the consequences of his ways; according to his deeds will [Jehovah] repay him. In the womb he supplanted his brother. (Hosea 12:2-3)
But Esau, or the charity that Esau represented, was still dominant, as can be seen in the enigmatic prediction of his father Isaac:
By your sword you will live, and your brother you will serve. And it will happen when you gain the dominance that you will force his yoke off your neck. (Genesis 27:40)
In other words, Esau represented a church among non-Jews, 2 or a new church, while Jacob represented the Jewish church. This is why it says so many times that they should acknowledge non-Jewish nations as their brothers and sisters. 3
In the church of the non-Jews, or the early [Christian] church, they all called each other "sister" or "brother," because of the charity among them. "Sisters and brothers" was also used by the Lord of those who hear the Word and act on it (Luke 8:21); the "hearers" are those who have faith, the "doers" those who have charity. However, those who hear (or say they have faith) and do not act on it (have no charity) are not "sisters and brothers," and the Lord compares them to fools (Matthew 7:24, 26).
1. The Hebrew of Jeremiah 13:14 says, literally, "And I will smash them, a man against his brother" (וְנִפַּצְתִּים אִישׁ אֶל-אָחִיו [vǝnippaṣtîm 'îš 'el-'āḥîv]). Both Isaiah 19:2 and Jeremiah 13:14 appear to use "a man" and "his brother" in a negative sense. [LHC]
3. It is not entirely clear which passages are referred to here, but the prophets sometimes speak of other nations as being equally under God's protection and mercy. Examples are Amos 9:7; Isaiah 19:23-25. The term translated here as "brothers and sisters" (and in other inclusive ways below) is fratres, which can apply collectively to siblings of either gender, and which also applies to people unrelated except by their common humanity. [LHC, LSW]