How do we know that the cross is central to Christian doctrine?

The cross of the Lord Jesus Christ is foundational to the Christian faith, articulating God's eternal purpose as stated in Revelation 13:8, where Christ is referred to as the Lamb slain from the foundation of the world. This underscores that God's plan for salvation was established before creation itself. Furthermore, the cross is the means by which God's attributes—such as His justice and mercy—are perfectly displayed. Every teaching in the scripture ultimately points back to the cross, revealing that understanding of God is incomplete without acknowledging the significance of Christ's sacrifice.