John 3:18--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.
Technically defined by Merriam-Webster, antithesis is "the rhetorical contrast of ideas by means of parallel arrangements of words, clauses, or sentences". Basically, it means you contrast two things by using structurally similar items. This is seen in the above verse. On one hand, you have a person who believes and is not condemned; on the other, you have a person who does not believe and is condemned. See how they're set up the same, but have opposite ideas? That's antithesis. The only thing added is the clause "because he hath not believed in the name of the only begotten Son of God."
This example of antithesis is extremely important, as it deals with the paramount topic of every living person: the destination of his or her eternal soul. In the first part, the reader is told that "he that believeth on him is not condemned". The one who is to be believed on is Jesus. This is wonderful news! Imagine you are standing in court, guilty of a heinous crime and sentenced to life in prison, or even death. Then someone walks in and tells you, "I have a way for you to be free. You will not be condemned. All you have to do is trust me." You do so, and it works; you're free! Wouldn't you be relieved?
In reality, we are all in the same situation, though actually much worse. We are all guilty of heinous crimes: breaking the perfect law of the holy God. The death sentence we have received for our sin is eternity in Hell, a place of never-ending suffering and torment. This is what is meant by the second clause in the verse, "but he that believeth not is condemned already". You see, even though you may be a "good person", you're still a sinner, and unless you've accepted Jesus Christ as Lord and Savior, you're already condemned to go to Hell. There's nothing you need to do to go there; you're already on your way!
But there is a way out. That's where your deliverer walks into the courtroom. That person is Jesus. Just like in the illustration above, Jesus is offering a way out of condemnation--out of Hell--for every person. The reason He can do so is because He is the perfect and righteous Son of God Who died for everyone's sins on the cross. Even though He was guiltless, He suffered the punishment that justice required for our crimes. All we have to do, like the verse says above, is believe on the Lord Jesus.
And yes, it is that easy. The verse simply states "he that believeth on him is not condemned". Nothing but faith in Jesus is needed. Someone once told me that other things were necessary for salvation because that verse didn't say that only believing was needed. But that is simply not true. If anything else were needed for salvation, then this verse would only be stating half the truth, and that would make it a lie. God cannot lie, and His Word is inerrant; therefore, faith is the only thing needed for salvation. You don't need baptism, church attendance, a good life, confirmation, confession, communion, or anything else--just believe.
All lives are parallel cases: everyone is guilty of sin and, because of this, condemned to eternity in Hell; all sins have also been paid for by the blood of Jesus, and salvation is offered to all. However, there is one thing that makes lives antithetical to one another: whether or not they accept the free gift of pardon offered by Jesus. That is the crucial point. Two lives can be lived exactly the same, yet one can suffer in Hell while the other rejoices in Heaven. This is perfectly seen in the two thieves crucified with Jesus. They were both criminals convicted for their crimes, but because one was penitent and believed on Jesus, he went to Heaven while the other perished in Hell.
If you have not accepted Jesus as your Savior, please do. Don't put it off a moment longer, because you never know when your last breath will be. Click the Salvation tab above for more information.
If you are saved, rejoice and thank God for His work of redemption in you! Take a special moment to get on your knees and humbly thank Him for rescuing you from an eternity in Hell, for taking all the punishment and wrath you so rightfully deserve. Then go tell someone about the wonderful and mighty God you serve. Tell them the greatest news ever to grace their ears: that they too can be free of sin and eternal death.