John Gill Commentary Isaiah 65:15

"And ye shall leave your name for a curse unto my chosen; and the Lord Jehovah will slay thee; and he will call his servants by another name:" — Isaiah 65:15 (ASV)

And you shall leave your name for a curse unto my chosen
Execrable and abominable to them, as the name of a Jew is to this day, and in all places; for their unbelief and impenitence, for their perfidy and insincerity, for their tricking and covetousness, and other crimes they are addicted to; see (Jeremiah 24:9) .

For the Lord God shall slay them
by the sword of the Romans, and by his judgments, which continue upon them; the Targum says, with the second death; and so Jarchi interprets it of eternal death, which is the just wages of sin.

And call his servants by another name
a new name, as the Septuagint and Arabic versions; the name of the people of God, the Gentiles formerly were not called by; but now all that believe in Christ, whether Jews or Gentiles, are his people; the name of the sons of God, a name better than that of sons and daughters of the greatest potentate; the name which the mouth of the Lord calls, "Hephzibah" and "Beulah", being delighted in by the Lord, and married to him; or rather the name of Christians, first given to the disciples of Christ at Antioch, and ever since continued, (Acts 11:26) .