John Calvin Commentary Isaiah 65:9

"And I will bring forth a seed out of Jacob, and out of Judah an inheritor of my mountains; and my chosen shall inherit it, and my servants shall dwell there." — Isaiah 65:9 (ASV)

And I will bring forth a seed out of Jacob. He explains the preceding verse in other words and shows that the Lord wishes to reserve for Himself some “seed” that will call upon Him; for the Lord is accustomed to chastise His people in such a manner as to ensure that the Church will exist, in which His truth and pure religion may be preserved, and which Paul for that very reason calls the pillar and foundation of truth. (1 Timothy 3:15). We must not, therefore, judge the Church from the present condition of things (for nothing in this world can be permanent), but from the purpose of God, which will not allow it to be overturned or destroyed. This ought to be carefully remembered by us, so that we may not be terrified by any calamities or ruins, or by any hideous desolation of the Church.

And out of Judah the heir of my mountains. He gives the name “heirs of the mountains” to those who, having returned from captivity, will again inhabit their native land. Judea, as is well known, was a mountainous country. He again explains what might have appeared to be somewhat obscure.

And my elect shall possess it by inheritance. He means that the Jews will return to their original condition, so that they may enjoy that country as their own inheritance, from which they had been driven out. Judea was soon afterwards reduced to the utmost desolation. The Lord testifies that this will not be of long duration; and, to confirm it further, He concisely mentions the covenant by which that land was destined for them, so that they might possess it by the right of inheritance. Thus, although they were long in captivity, yet this word “inheritance” ought to arouse them to cherish the confident hope that they would eventually regain possession of it. But it ought to be observed that this grace is confined to the elect and true worshippers of God, so that not everyone may apply it to himself without distinction.