Answer: A liar is the man who denies that Jesus is the Christ, (verse 22).
MORE INFORMATION AND/OR OTHER SCRIPTURE REFERENCES:
John 17:3: [Jesus, praying to God, said,] "Now this is eternal life: that they may know You, the Only True God, and Jesus Christ, Whom You have sent."
John 20:31: "But these are written that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in His Name."
Acts 5:41-42: "The apostles left the Sanhedrin, rejoicing because they had been counted worthy of suffering disgrace for the Name. Day after day, in the temple courts and from house to house, they never stopped teaching and proclaiming the Good News that Jesus is the Christ."
