This is God’s judgment or evaluation of believers ONLY, and is based on the execution of God’s Pre-Designed Plan for the believer, or the failure to execute said plan. The purpose is to cleanse by fire all human good and separate human good from Divine Good. It is based on rewards or loss of rewards for all eternity (not salvation — not sin). Rewards not received as God planned become a memorial to His Plan. Sin is not the issue, because sin’s penalty was paid for on the Cross. Christ died spiritually, then physically, when He exhaled saying “It is finished!” God the Father was “propitiated” (perfectly satisfied) with Christ’s life and death as witnessed by the Resurrection, Ascension, and current session of Christ at the right hand of God.
(Please note: The Judgment Seat Of Christ is for believers only. The Great White Throne Judgment is for unbelievers only.)