How do we know that Christ's atonement is for the elect only?

Historical Reformed theology emphasizes that Christ's atonement is specifically for the elect, a belief supported by several scriptures. Passages like Matthew 1:21 affirm that He will save His people from their sins. Ephesians 1:4-5 states that God chose His people in Christ before the foundation of the world. This demonstrates that the atoning sacrifice of Christ was planned for the elect, ensuring that all for whom He died will definitely come to faith and be saved. The nature of Christ's sacrifice as not merely universal but particular affirms that it effectively secures salvation for His chosen ones.