Many people struggle with the assurance of their salvation. It is a huge problem. Some Christians teach that it is good to have doubts about your salvation using 2 Corinthians 13:5. But that is not at all what that passage teaches. 

You will see that there are many reasons why people may doubt their salvation. Doubts are spiritually crippling, but assurance is essential to the gospel and to growth in Christ. When we understand the gospel of grace, we will have assurance. It is not helpful to look at our works or try to evaluate our faith. We have to keep our eyes on Jesus Christ. First John 5:11-13 and Romans 8:31-39 are important passages that help those in doubt.