He that believes on him is not condemned: but he that believes not is condemned already, because he has not believed in the name of the only begotten Son of God.
All Commentaries on John 3:18 Go To John 3
Cyril of Alexandria
AD 444
Having proved by facts, that He is both Son of God the Father, and introduceth into the world grace which is more excellent than the ministration of Moses (for how is not the being justified by grace better than the being condemned by the law?), He devised, as God, another way to bring unto the faith, from all quarters driving together to salvation them that were lost. He puts forth then to the believer as his reward the not being called to judgement, to the unbeliever punishment, bringing into one and the same way by both, calling to come readily unto the faith, some by desire for the grace, others by fear of suffering. He shews that heinous and great is the crime of unbelief, since He is Son and Only Begotten. For by how much is that worthy of belief which is insulted, so much the more will that which despises be condemned for his dire transgression. He says that he that believeth not is condemned already, in that he hath already determined against himself the due sentence of punishment, by knowingly rejecting Him Who gives not to be condemned.