According to the Gospels of Matthew and Mark, Judas identifies Jesus with a kiss (cf. Matt 26:48-49; Mk 14:44-45). This gesture may seem inappropriate given the circumstances—kisses are usually expressions of love rather than betrayal—however, Judas’s kiss underscores Jesus’ role as the King of the Jews and portends his upcoming battle against sin at Golgotha.
When Judas arrives at Gethsemane, he tells the accompanying crowd, “The one I will kiss (φιλήσω; philéso) is he; seize him” (Matt 26:48). Then, Judas “kissed him” (κατεφίλησεν αὐτόν; katephílesen autón 26:49). The Greek word for “to kiss” (φιλέω; philéo) also means “to love,” so it’s ironic that Judas chooses this gesture to mark his disloyalty to Jesus. Luke flags this irony when Yeshua asks, “Judas, would you betray the Son of Man with a kiss (φιλήματι; philémati)?” (Lk 22:48). While, in one sense, the betrayer’s behavior appears out of place, it is also appropriate insofar as the kiss recalls one of the rituals of royal coronation and foreshadows the references to Jesus as “King of the Jews” before his crucifixion.
When Samuel installs Saul as king of Israel, “Samuel took a flask of oil and poured it on [Saul’s] head and kissed him (ἐφίλησεν αὐτὸν; epílesen autòn) and said, ‘Has not the Lord anointed you to be prince over his people Israel?’” (1 Sam 10:1 LXX). In the context of Israel’s Scriptures, Samuel kisses Saul in an anointing ceremony, so it is fitting for Yeshua the “Messiah” (משׁיח; mashiach)—literally, the “Anointed One”—to receive a kiss from Judas. Samuel goes on to tell Saul, “You shall reign over the people of the Lord and you will save (σώσεις; sóseis) them from the hand of their surrounding enemies” (1 Sam 10:1). Just as Samuel kisses Saul to inaugurate his job to save his people from their enemies, Judas kisses Jesus before he goes to the cross to “save (σώσει; sósei) his people from their sins” (Matt 1:21). In recapitulating Samuel’s act toward Saul, Judas’s kiss highlights Jesus’ kingship and precedes the messianic mission of salvation.
Of course, Judas's kiss for Jesus was meant to be an act of betrayal, not an affirmation of royal status. In this way, the defective disciple enacts a perversion of Samuel's positive gesture toward king Saul. Still, what Judas meant for evil, God used for good (cf. Genesis 50:20). The kiss in Gethsemane is a negative echo of Samuel's coronation, but Jesus' arrest will lead to his enthronement as a "King of the Jews" whose death will bring about salvation from sin.