Salvation comes by faith alone in Jesus Christ—through His grace alone. Genuine conversion rests completely in what Christ did, not in what we do (or fail to do). But our salvation will also be evidenced in our lives.
First, if we believe that Jesus died for our sins and rose again from the dead and confess Him as Lord, we can be sure of our salvation (Romans 10:9-11). We can take God at His Word—His Word does not fail. He has said that Christ’s sacrifice is sufficient to wash you white as snow (Hebrews 10:19-25). If you believe this, you are saved.
Second, the Bible promises that the Holy Spirit gives us confirmation that we are children of God (Romans 8:16). Similarly, in Galatians 5, Paul describes what is commonly known as the Fruit of the Spirit—characteristics that the Holy Spirit fosters in our hearts when we receive Christ and determine to walk in His ways. These attributes are supernatural in that they run in contradiction to human nature, so these fruit—love, joy, peace, patience, kindness, goodness, gentleness, faithfulness, and self-control—are evidence of a true believer.