“He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God." (John 3:18)
In the above scripture, Jesus was talking to a Pharisee (religious leader) by the name of Nicodemus who was a member of the powerful Jewish council. Nicodemus was attracted by Jesus' character and miracles. Now, Nicodemus was afraid that someone would find out that he was talking to Jesus, so he made arrangements to see Jesus during the night. Nicodemus didn't want anyone to know that he was a follower of Jesus.
After this secret meeting with Jesus, Nicodemus walked away with a different attitude regarding who Jesus really was. For you see, Nicodemus was a very religious man, but Jesus explained to him that "religion" was not going to get him into Heaven. Jesus let Nicodemus know that he must be "born again" and put his faith in the Son of God. Jesus told Nicodemus that whoever believed in Him (Jesus) would not be condemned, but those that did not believe in Him were condemned already.
Now the word "condemned" is defined as - showing a strong disapproval or demonstrates the guilt of someone. The Bible tells us that we have all sinned and fallen short of the glory of God. That means that we are all sinners and are condemned to be separated eternally from God. The original sin all started with Adam and Eve back in the Garden of Eden. Since that time everyone is born with a "sin nature" that keeps them separated from our Holy God.
So what Jesus was telling Nicodemus was, that the only way not to be condemned or separated from God, was to believe in Him (Jesus). Jesus made it very clear that those that refused to believe in Him were condemned already. In this chapter of John, Jesus was referring to those who had heard the Gospel and have deliberately and knowingly rejected it.
Father God, it is my prayer that I never hide the fact that I am a disciple of our Lord Jesus. I pray that You give me the wisdom and courage to go out and witness to a condemned and lost world.