How do we know that Christ died only for the elect?

The doctrine of particular redemption asserts that Christ's substitutionary death is specifically for those whom the Father has chosen. This is rooted in Scriptures where it's clear that Jesus states His purpose is to redeem His people (Matthew 1:21). The concept that 'Christ died for everyone' contradicts the idea of a true substitution, as He identifies His bride, the church, as only those given to Him (Ephesians 1:4-5). Christ's sacrifice is sufficient to save all, yet it is efficient only for the elect, satisfying God's justice uniquely for them.