When we speak of assurance, we are speaking of that which we know because the evidence is clear. This is the heart of First John and the other passages dealing with this subject. The way to tell if you are a Christian is not to look at the sincerity of a decision, but to look at the change in the life. As far as I can tell, there is no teaching in the Word which says that you can be sure that you are a Christian by looking back at an historical conversion experience. “These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life...” (1 Jn. 5:13, emphasis mine). What things? Those tests which make up the content of the epistle. In other words, one’s assurance should be based on discernible factors which can be tested.