Charles Ellicott Commentary Matthew 27:43

"He trusteth on God; let him deliver him now, if he desireth him: for he said, I am the Son of God." — Matthew 27:43 (ASV)

Let him deliver him now — At first, it seems hardly conceivable that the priests and scribes could have quoted the very words of Psalm 22:8, and in doing so, fulfilled one of the great Messianic prophecies. However, we must consider two points:

1. Since they ignored the idea of a suffering Christ, they would not have viewed the Psalm as Messianic at all.
2. Their deep familiarity with the words of the Psalm would have naturally brought its phrasing to their lips when the occasion arose.

They would simply have persuaded themselves that they were right in using these words, while David’s enemies had been wrong.