Jesus says that He guarded those given to Him and that none was lost except 'the son of perdition,' so that Scripture might be fulfilled. The reference concerns Judas, whose betrayal has already unfolded during the Farewell Narrative.
Jesus in Context
The Son of Perdition and the Fulfillment of Scripture
Jesus refers to Judas with the Semitic-style expression “son of perdition” and places his betrayal within the Gospel's pattern of Scripture being fulfilled.
Introduction
Historical and Cultural Context
Biblical and Semitic speech frequently uses expressions such as 'son of' something to describe a person characterized by a quality, condition, or destiny. The expression 'son of perdition' therefore does not mean that Perdition is literally a parent. It characterizes Judas in relation to destruction or ruin.
John has already connected Judas' betrayal with Scripture in John 13:18, where Jesus cites Psalm 41:9 concerning one who shared His bread and then turned against Him.
Why It Matters
Understanding the idiom prevents a wooden reading of 'son of perdition.' At the same time, the reference to fulfilled Scripture places Judas' betrayal within John's larger presentation of Jesus' passion as neither an accident nor a development that catches Jesus unaware.