Charles Spurgeon Commentary Isaiah 54:15

"Behold, they may gather together, but not by me: whosoever shall gather together against thee shall fall because of thee." — Isaiah 54:15 (ASV)

Whosoever shall gather together against thee shall fall for thy sake.

Oh, how often, and how mysteriously, and how terribly God has smitten the enemies of his people! The hand of the Lord has gone out against them as it went out against Sennacherib and his host, in the days of good king Hezekiah.

Behold, they shall surely gather together,

You will have enemies, even if you lead the most blameless life that can be lived; for the absolutely blameless One had many cruel enemies who hounded him to death.

But not by me:

God is not with them, for he is on your side.