Israel was and is the only family which will be saved. It is the "tame olive tree" that the Lord "took and nourished in his vineyard." (5: 3.) Despite all the Lord's efforts, however, the actual family tree "waxed old, and began to decay." (Id.) It lost its vitality. It tired of the Lord. His desire and "nourishment" was not able to overcome the tree's indifference to what He offered them. It began to decay.
The Lord was unwilling to abandon His tree even when there was no productivity in it. He intended to continue to create the Family of God, despite the failure by the family to respond to His invitation. He initially set about to "prune it" (that is, to cast away from the Family of God or Israel, those who failed to live worthily) and to "dig about it" and then to "nourish it." In the initial work it is the Lord directly who does the work. He does not send a servant to perform the labor. (5: 4-5.)
"Pruning" involves cutting away. It destroys. The goal is ultimately to bring about vigor and life. But the initial work requires destroying to clear away and make the growth possible. The result is harsh and violent in the short run, but there is something important going on in the work of "pruning" away. The larger purpose is what the Lord has in mind. The short term sacrifices and difficulties are unavoidable and necessary. They must be endured.
"Digging about" the tree is also violent. It is threatening, and imposes upset and difficulties. The Lord's benign intent is not understood when the pruning and digging are measured against short term standards. They must take a longer view.
The Lord's purpose is to "perhaps" produce "young and tender branches." (5: 5.) It is "perhaps" because the Lord grants the tree agency to respond, not compulsion to force compliance. The Lord can coax, but the tree must grow.
The older branches are not intended to be preserved. They bear nothing but bad fruit. The young and tender branches are the goal. These, however, will not yield fruit for some time. They must have an opportunity to develop.
This description of ancient Israel shows how the Lord's work was always purposeful and designed to preserve the tree and continue to create sons and daughters of God. However, despite all He did, the "little, young and tender branches" were comparatively small in the scheme of things. As to the "main top thereof" it "began to perish." (5: 6.)
The infrastructure, the hierarchy, the temple, the priestly class, the learned Rabbis and the schools of thought were rotting. They were nothing like what would be required to produce fruit. They were religious but heritical. They were devoted, but not His sons and daughters. The family line was broken. They needed to be adopted back again, because they lacked the power to remain connected.
This is an odd juxtaposition: The "main top" is corrupt. The "young tender branches" are nothing like the great growth overshadowing them. Yet the Lord sees in the young growth what He seeks. As to the "main top" there is nothing but "perishing" and decay.
Israel is so often in this predicament. They despise the truth, but respond warmly to flattery telling them they are righteous. (Hel. 13: 27-28.) When someone is sent by the Lord of the vineyard calling for repentance, Israel rejects him, says he is a sinner and a false prophet. (Hel. 13: 25-26.) Ultimately, however, for the bloodline of Jacob to rise up and become fruit worthy of preservation, there must be a change from blood connection to Jacob to an adoption into Israel. Then they become sons and daughters of God, and fruit worthy of preservation. (Mosiah 27: 25.)