Contradiction with Isaiah 49:14
While Isaiah 54:6 suggests temporary forsaking, Isaiah 49:14 speaks of Zion feeling permanently forgotten by God.
Isaiah 49:14: But Zion said, The LORD hath forsaken me, and my Lord hath forgotten me.
Contradiction with Isaiah 62:4
Isaiah 54:6 mentions being "forsaken," while Isaiah 62:4 declares that God's people shall no longer be termed "Forsaken."
Isaiah 62:4: Thou shalt no more be termed Forsaken; neither shall thy land any more be termed Desolate: but thou shalt be called Hephzibah, and thy land Beulah: for the LORD delighteth in thee, and thy land shall be married. [Hephzibah: that is, My delight is in her] [Beulah: that is, Married]
Contradiction with Hebrews 13:5
Isaiah 54:6 describes forsaking, but Hebrews 13:5 promises that God will never leave nor forsake, providing a sense of permanent presence.
Hebrews 13:5: [Let your] conversation [be] without covetousness; [and be] content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee.
Contradiction with Psalm 27:10
Isaiah 54:6 speaks of God forsaking for a moment, whereas Psalm 27:10 implies the enduring nature of God's gathering and not forsaking.
Psalm 27:10: When my father and my mother forsake me, then the LORD will take me up. [take...: Heb. gather me]