How do we know Jesus' sacrifice was effective for all believers?

The effectiveness of Jesus' sacrifice hinges on the doctrine of particular redemption. Scriptures like 1 John 2:2 affirm that Christ is the propitiation for our sins, indicating that He died specifically for the sins of His people. This affirms that His atonement is not a mere possibility; it accomplishes salvation for those chosen before the foundation of the world, as stated in Ephesians 1:4-5. This assures believers that God's intent in sending Christ was to successfully redeem His elect, ensuring that none for whom Christ died will perish.