Albert Barnes Commentary John 3:8

"The wind bloweth where it will, and thou hearest the voice thereof, but knowest not whence it cometh, and whither it goeth: so is every one that is born of the Spirit." — John 3:8 (ASV)

The wind bloweth, etc. Nicodemus had objected to the doctrine because he did not understand how it could be. Jesus shows him that he ought not to reject it on that account, for he constantly believed things quite as difficult. It might appear incomprehensible, but it was to be judged by its effects.

As in this case of the wind, the effects were seen, the sound was heard, important changes were produced by it, trees and clouds were moved, yet the wind is not seen, nor do we know from where it comes, nor by what laws it is governed; so it is with the operations of the Spirit.

We see the changes produced: Men just now sinful become holy; the thoughtless become serious; the licentious become pure; the vicious, moral; the moral, religious; the prayerless, prayerful; the rebellious and obstinate, meek, and mild, and gentle. When we see such changes, we ought no longer to doubt that they are produced by some cause—by some mighty agent—than when we see the trees moved, or the waters of the ocean piled on heaps, or feel the cooling effects of a summer’s breeze. In those cases we attribute it to the wind, though we do not see it, and though we do not understand its operations. We may learn from this:

1. That the proper evidence of conversion is the effect on the life.

2. That we are not to search too curiously for the cause or manner of the change.

3. That God has power over the most hardened sinner to change him, as he has power over the loftiest oak to bring it down by a sweeping blast.

4. That there may be great variety in the modes of the operation of the Spirit. As the wind sometimes sweeps with a tempest, and prostrates all before it, and sometimes breathes upon us in a mild evening zephyr, so it is with the operations of the Spirit. The sinner sometimes trembles and is prostrate before the truth, and sometimes is sweetly and gently drawn to the cross of Jesus.

Where it listeth. Where it wills or pleases. So is every one, etc. Everyone who is born of the Spirit is, in some respects, like the effects of the wind. You do not see it, you cannot discern its laws, but you see its effects, and you therefore know that it does exist and operate.

Nicodemus's objection was that he could not see this change, or perceive how it could be. Jesus tells him that he should not reject a doctrine merely because he could not understand it. Neither could the wind be seen, but its effects were well known, and no one doubted the existence or the power of the agent .