How do we know the faith once delivered is true?

The faith once delivered refers to the body of truth established by God's revelation throughout history, culminating in the life and work of Jesus Christ. Jude exhorts believers to contend for this faith because it encompasses essential doctrines that affirm God's sovereignty and the effectiveness of Christ's redemptive work. This faith is attested to by scripture and historically affirmed by the Church as an immutable testimony of God's covenant grace, which cannot be altered or diminished. To reject this faith is to undermine both the glory of God and the full salvation accomplished in Christ.