Assurance of salvation is the settled, Spirit-wrought confidence that one is truly a child of God. It is not the same as salvation itself — some true believers struggle with assurance, and some false professors possess false assurance. But genuine assurance is the normal inheritance of mature Christians, and Scripture teaches us to pursue it. The writer of 1 John wrote his entire epistle "that you may know that you have eternal life, and that you may continue to believe in the name of the Son of God" (1 John 5:13). The Westminster Confession captures the classic Protestant position: "Such as truly believe in the Lord Jesus, and love Him in sincerity, endeavoring to walk in all good conscience before Him, may, in this life, be certainly assured that they are in the state of grace... and that by the infallible assurance of faith founded upon the divine truth of the promises of salvation, the inward evidence of those graces unto which these promises are made, the testimony of the Spirit of adoption witnessing with our spirits that we are the children of God." Three legs hold up biblical assurance: (1) The promises of Scripture — what God has said He will do for those who trust Christ. "He who believes in the Son has everlasting life" (John 3:36). (2) The internal witness of the Holy Spirit — "The Spirit Himself bears witness with our spirit that we are children of God" (Romans 8:16). (3) The evidence of changed life — the fruit of the Spirit, love for the brethren, hatred of sin, delight in God's Word. 1 John repeats several tests of genuine faith: do we keep His commandments? do we love the brethren? do we confess Christ come in the flesh? Assurance is not a one-time event but a grace that grows. Christians who doubt their salvation should not repress the doubt but should confront it with the Word, confess sin, and fly to Christ afresh. "I believe; help my unbelief!" (Mark 9:24) is a prayer God answers.