In 1 John 5:13 the Spirit, through John, informs us that we can know if we have true saving faith.
In the rest of 1 John the Spirit listed many little clues that, if you see them, probably indicate that the faith you claim to have is indeed genuine, saving, faith.
Here is a summary of them.
The Fruit of Faith from 1 John (5:13)
- Is your faith defined in terms of a relationship with God? (1:3; 3:1)
- Are you sensitive to sin? (1:8-10)
- Are you growing in obedience / holiness? (2:3-6; 3:3, 6)
- Are you growing in discernment? (2:21; 4:1)
- Do you eagerly expect Christ’s return? (2:28-3:3)
- Do you pray for things God promised and experience His answer? (5:14-15)
- Do you experience a growing distance to the world? (2:15-17; 3:13; 5:19)
- Do you love other Christians? (3:1, 17-18)
NOTE: None of these can give faith, but they are the fruit that prove that the faith one claims is genuine.
Pray that they convict, and confirm, where necessary.