Assurance of salvation

I write these things so that you may know that you have eternal life.

I have written these things to you who believe in the name of the Son of God, so that you may know that you have eternal life.
1 John 5:13

The Spirit Himself testifies with our spirit that we are God’s children.
Romans 8:16

Therefore, brothers, strive to make your calling and election sure. For if you practice these things you will never stumble,
2 Peter 1:10

We want each of you to show this same diligence to the very end, in order to make your hope sure.
Hebrews 6:11

So when God wanted to make the unchanging nature of His purpose very clear to the heirs of the promise, He guaranteed it with an oath. Thus by two unchangeable things in which it is impossible for God to lie, we who have fled to take hold of the hope set before us may be strongly encouraged. We have this hope as an anchor for the soul, firm and secure. It enters the inner sanctuary behind the curtain,
Hebrews 6:17–19