"For God so loved the world that he gave his only Son, so that everyone who believes in him may not perish but may have eternal life. Indeed, God did not send the Son into the world to condemn the world, but in order that the world might be saved through him. Those who believe in him are not condemned; but those who do not believe are condemned already, because they have not believed in the name of the only Son of God" (John 3:16-18).
I am frequently asked about verse 3:16, but this is the first time I've been asked about verses 17-18, which really complete the thought.
The central question, of course, is what is meant by "his only Son." Traditional Christians believe it can only refer to Jesus, but metaphysically the reference is to the Christ, which is the true identity of each of us. It is as the Christ that each of us is empowered to "save" the world by standing firm in this spiritual Truth, for ourselves and for others. "Those who do not believe" in their own spiritual power because they are choosing to live without that belief in themselves as "the only Son of God."