He that believes on him is not condemned: but he that believes not is condemned already…
In primitive times there was a law or custom that if a man or woman would consent to marry, under the gallows, a person condemned to death, the criminal would thereby be saved from execution. There are instances on record of this custom having been carried out. We have here a faint picture of the grand truths of the text. The sinner "is condemned already," is under sentence of death, but Christ consents to raise him into union with Himself, and so thereby deliver him from his terrible doom, but faith working through love must be the bond of this mystical union. And this faith regenerates the man. By it the greatest sinner is transformed into a saint.
(A. J. Parry.)
Parallel VersesKJV: He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.