How do we know Judas Iscariot was not a true believer?

The New Testament presents Judas not as a victim of circumstances but as one who, despite being chosen as a disciple, ultimately rejected Christ. His betrayal was a calculated act, signifying a heart far removed from genuine belief. Matthew 27:3-5 details Judas's remorse, but rather than repent towards Christ, he sinks into despair. His story aligns with the Biblical theme that those who genuinely belong to Christ will remain steadfast in faith; Judas's departure illustrates the reality of false discipleship within the visible church.