Hebrews 10:19-25, 1 John 5:11-13
Assurance of salvation is simply this: Knowing for sure, being convinced, that you are saved, that you stand forever graciously and undeservedly justified before God by the work of Christ on your behalf, that by faith alone you are now perfectly loved in the Beloved, standing immovable within the sphere of God’s acceptance and eternal sonship. That you are, indeed a child of God and joint-heir with Jesus the Son.
Many Christians throughout history have written and cried out about their struggles in being assured of their salvation. The problem is that many followers of Jesus Christ look for the assurance of salvation in the wrong places. And some preachers and teachers not only encourage but insist that they look to wrong places.