A.T. Robertson Commentary Galatians 3:21

"Is the law then against the promises of God? God forbid: for if there had been a law given which could make alive, verily righteousness would have been of the law." — Galatians 3:21 (ASV)

Against the promises (κατα των επαγγελιων). A pertinent question again. Far from it (μη γενοιτο).

Which could make alive (ο δυναμενος ζωοποιησα). First aorist active infinitive of ζωοποιεω, late compound (ζωος, alive, ποιεω, to make) verb for which see 1 Corinthians 15:22. Spiritual life, he means, here and hereafter.

Verily (οντως). "Really" (cf. Mr 11:32; Luke 24:34). Condition and conclusion (αν ην) of second class, determined as unfulfilled. He had already said that Christ died to no purpose in that case (2:21).