AMEN! I hadn't read your posting of Isaiah 46 until now. Truly, as you remind us, God's will is irresistible because He is God, and God gets what He wants, one way or another.
Sometimes I think it must be difficult to comprehend the New Testament if we do not have a solid understanding of who God revealed Himself to be in the Old Testament. It is the same God. And the same salvation -- all by grace alone through faith alone in "the Lamb slain from the foundation of the world."
And he is before all things, and by him all things consist." -- Colossians 1:16-17"For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him:
To God be the glory!