What does the Bible say about eternal security in Christ?

Eternal security, or the perseverance of the saints, is a key doctrine in Reformed theology. John 6:39 states, 'This is the Father's will which hath sent me, that of all which He hath given me, I should lose nothing, but should raise it up again at the last day.' This assurance is rooted in the divine promise of God, affirming that those whom He has chosen will be preserved until the end. When we understand that our salvation is not contingent upon our actions but upon Christ's finished work on the cross, we find true security. Jesus says in John 10:28, 'I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand.' Therefore, the believer’s security is based on God’s power rather than human effort, affirming that our salvation is irrevocable.