John 12:44-50 (NKJV)
Then Jesus cried out and said, "He who believes in Me, believes not in Me but in Him who sent Me. And he who sees Me sees Him who sent Me. I have come as a light into the world, that whoever believes in Me should not abide in darkness. And if anyone hears My words and does not believe, I do not judge him; for I did not come to judge the world but to save the world. He who rejects Me, and does not receive My words, has that which judges him-- the word that I have spoken will judge him in the last day. For I have not spoken on My own authority; but the Father who sent Me gave Me a command, what I should say and what I should speak. And I know that His command is everlasting life. Therefore, whatever I speak, just as the Father has told Me, so I speak."
Jesus speaks clearly and plainly. To hear what He says and not believe it is the same as rejecting Him. Jesus says that is all that is needed for judgment, your decision about what to do with Jesus. He says too, that what you have heard Him say is the same as hearing God the Father say it. It is a matter of everlasting life or everlasting death.
Notice that we are judged not by our good deeds, but by our response to the Word of God.
This is Jesus' last public invitation to believe in Him and notice the passion with which He gives it: "Then Jesus cried out and said." He cried out, pleading that those who would hear Him should believe in Him. Jesus came to save, not to judge. Rejecting Him however will result in judgment.