There are some who say that it is arrogant to say that we can know that we are saved, but the bible says otherwise. John in the duly named epistle of 1 John declares "I write these things to you who believe in the name of the Son of God that you may know that you have eternal life" chapter 5, verse 13. The previous chapters detail the information that will aid us in our being able to say "I know that I am saved" honestly and without reservation. 1 John is one of my favorite books in all of scripture, I encourage anybody to take time out of their day and read it.