How do we know the power of the cross is true?

The truth of the power of the cross lies in the resurrection of Jesus Christ and the promises of Scripture regarding His atoning work. The cross was not a mere attempt to potentially save everyone; rather, it was a definitive action that secured the redemption of those whom God had chosen before the foundation of the world. Romans 5:10 confirms that 'For if when we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life.' This showcases that the death of Christ was both a payment for sin and a means of securing the elect's salvation. Thus, the effectiveness of the sacrifice is proven by His resurrection, which declares the acceptance of His offering by the Father.