How do we know that a true believer cannot lose their salvation?

The assurance of salvation for true believers is grounded in the words of Jesus, who stated, 'I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand.' This affirms the security of those who are genuinely His. The doctrine of the perseverance of the saints is critical in understanding that true believers, under God's sovereignty, are kept for eternity. Those who may depart, like Judas, were never truly part of the fold, demonstrating that salvation is an act of God's sovereign grace.