Contradiction with Exodus 34:6-7
While Isaiah 9:17 speaks of God's anger and no mercy, Exodus 34:6-7 describes God as merciful and gracious, forgiving iniquity and transgression.
Exodus 34:6-7: And the LORD passed by before him, and proclaimed, The LORD, The LORD God, merciful and gracious, longsuffering, and abundant in goodness and truth,
Contradiction with Psalm 103:8
Isaiah 9:17 depicts God's wrath, but Psalm 103:8 highlights God's merciful and gracious nature, slow to anger.
Psalm 103:8: The LORD [is] merciful and gracious, slow to anger, and plenteous in mercy. [plentious...: Heb. great in mercy]
Contradiction with Micah 7:18
Isaiah 9:17 shows no mercy, contrasting with Micah 7:18 where God is portrayed as one who pardons iniquity and delights in mercy.
Micah 7:18: Who [is] a God like unto thee, that pardoneth iniquity, and passeth by the transgression of the remnant of his heritage? he retaineth not his anger for ever, because he delighteth [in] mercy.
Contradiction with James 5:11
Isaiah 9:17 implies relentless anger, whereas James 5:11 emphasizes the Lord's purpose as being full of compassion and mercy.
James 5:11: Behold, we count them happy which endure. Ye have heard of the patience of Job, and have seen the end of the Lord; that the Lord is very pitiful, and of tender mercy.