Contradiction with Matthew 28:19
Isaiah 51:5 speaks of God's arm bringing judgment and salvation without explicit mention of the trinity, whereas Matthew 28:19 emphasizes the triune nature of God--Father, Son, and Holy Spirit--in salvation and baptism.
Matthew 28:19: Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: [teach...: or, make disciples, or, Christians of all nations]
Contradiction with Romans 11:25-26
Isaiah 51:5 speaks of imminent salvation and judgment, but Romans 11:25-26 refers to a partial hardening of Israel until the fullness of the Gentiles comes in, implying a longer process.
Romans 11:25-26: For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. [blindness: or, hardness]
Contradiction with 2 Peter 3:9
Isaiah 51:5 suggests an immediate revelation of God's judgment and salvation, while 2 Peter 3:9 emphasizes God's patience and delay for the sake of repentance.
2 Peter 3:9: The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
Contradiction with Revelation 22:12
While Isaiah 51:5 speaks of salvation and judgment arriving with God's arm, Revelation 22:12 emphasizes Jesus's return with rewards based on individual works, focusing more on personal accountability.
Revelation 22:12: And, behold, I come quickly; and my reward [is] with me, to give every man according as his work shall be.