John Calvin Commentary Galatians 5:25

"If we live by the Spirit, by the Spirit let us also walk." — Galatians 5:25 (ASV)

If we live in the Spirit. According to his usual custom, the apostle draws from the doctrine a practical exhortation. The death of the flesh is the life of the Spirit. If the Spirit of God lives in us, let him govern our actions.

There will always be many persons daring enough to make a false boast of living in the Spirit, but the apostle challenges them to a proof of the fact. Just as the soul does not remain idle in the body, but gives motion and vigor to every member and part, so the Spirit of God cannot dwell in us without manifesting himself by the outward effects.

By the life is meant here the inward power, and by the walk the outward actions. The metaphorical use of the word walk, which frequently occurs, describes works as evidence of the spiritual life.