How do we know that Jesus' sacrifice guarantees salvation for the elect?

Jesus' declaration in John 10:27-28, where He states that no one can snatch His sheep from His hand, illustrates the security of the believer. This aligns with the teachings in Isaiah 53, emphasizing that His sacrificial act was not in vain but bore the benefit of secured salvation for those given to Him by the Father. The certainty of salvation springs from the efficacy of Christ's sacrifice—those for whom He died will surely be saved, bringing peace to the believer amidst life's uncertainties.