Jude who is also called Judas was physical brother to
the Lord as well as to another one of His servants - James (Jude 1 cf.Matthew 13:55;Mark 6:3); this James was the author of an epistle (James 1:1) and a "pillar" of the Jerusalem church (Galatians 2:9 cf.Acts 15:13)
"Mercy and peace" or "grace and peace"
are to be MULTIPLIED through the KNOWLEDGE of God and His Son (Jude 2 cf.II Peter 1:2)
Jude's desire was to write further concerning the GLORY
of Israel's SALVATION to be revealed "in the LAST TIME" at the Lord's appearing, which was spoken of
by the prophets (Jude 3 cf.I Peter 1:5-13)
However, Jude found it needful to write concerning the
necessity to CONTEND (STRUGGLE) for the FAITH, which they (Israel) have ALREADY RECEIVED (Jude 3 cf.Hebrews 12:1-8)
Jude warns against UNGODLY MEN quietly infiltrating the
assemblies of believers and CHANGING the GRACE of God INTO LASCIVIOUSNESS (Jude 4), who Peter describes as FALSE TEACHERS (II Peter 2:1) wresting Paul's writings to their own PERDITION (II Peter 3:15-16)
The GRACE of God spoken of by Paul to the Gentiles (Ephesians 3:1-2)
concerns their SPIRITUAL blessings in the HEAVENLY places (Ephesians 1:3) where they are SEATED WITH CHRIST (Ephesians 2:6), according to the "EXCEEDING riches of His GRACE" (Ephesians 2:7)
ALL is received UNCONDITIONALLY "by GRACE ... through
FAITH" as "the GIFT of God, NOT of WORKS" (Ephesians 2:8-9 cf.Colossians 2:6-7)
The GRACE of God spoken of by the prophets to Israel concerns
her being called "out of darkness into His marvellous light" to be a ROYAL PRIESTLY NATION (I Peter 2:9-10 cf.Hosea 1:9-10;Hosea 2:23),
i.e. His "PECULIAR TREASURE ABOVE ALL PEOPLE" of the EARTH (Exodus 19:5-6) as the "PRIESTS OF THE LORD" (Isaiah 61:6)
Israel's being God's channel of BLESSING to the nations,
according to God's COVENANT made with "THE FATHERS" (Acts 3:25 cf.Genesis 12:3;Genesis 26:4;Genesis 28:14)
is CONDITIONAL UPON her NATIONAL REPENTANCE for what she did to her Messiah (Acts 3:17-21)
God said that He would return to His place UNTIL Israel
will ACKNOWLEDGE her OFFENSE against Him and that she would seek Him soon in her AFFLICTION (Hosea 5:15)
- note a possible 2000 year interval between Messiah's two comings (II Peter 3:8-9 cf.Hosea 6:1-2)
and Israel's ANGUISHED REPENTANT CRY just prior to Messiah's return (Isaiah 64)
God will respond to REPENTANT Israel by destroying her
enemies (Zechariah 12:8-9) and pouring out upon her "the Spirit of GRACE" and she will
FINALLY ACKNOWLEDGE her OFFENSE against Him and will NATIONALLY MOURN for Him as she did for Josiah (Zechariah 12:10-14 cf.II Chronicles 35:24-25)
Note God's similar prophecy concerning Josiah to be used
as His instrument for the PURGING of Israel's SIN of IDOLATRY introduced by Jeroboam (II Kings 23:19-20;I Kings 13:1-2)