What does the Bible say about complete salvation?

The concept of complete salvation is firmly rooted in the teachings of the Apostle Paul, particularly in Galatians 3:3, where he rebukes the Galatians for believing they could be made perfect by their own efforts after beginning in the Spirit. True salvation, according to Scriptures like Ephesians 2:8-10 and Colossians 2:10, is a work of grace that is entirely the work of Christ, ensuring that all who are His are fully saved, justified, and sanctified in Him. This means that no works or additional efforts on the believer's part are needed for salvation, as Christ's sacrifice was complete and perfect.