What does the Bible say about the assurance of salvation for the righteous?

The assurance of salvation for the righteous is emphatically stated in Romans 8:33-39, where it is affirmed that God justifies His elect and that no one can bring a charge against them. The Bible emphasizes that there is no condemnation for those in Christ Jesus, and nothing can separate the righteous from the love of God. This assurance stems from the completeness of Christ's work—His life, death, and resurrection secured the salvation of believers and ensures their eternal security, despite the challenges they may face in this world.