Why is this a scary thought to you?
Do you deny God's election?
1) If you do not understand you belong to Christ you are instructed to examine yourself to see if you are in the faith. It means that you may be going through the motions and do not rest upon the saving grace of our Lord Jesus.
2) If you do not know that you are of the elect, not only is everything I stated in #1 applicable, but you don't believe the scriptures that talks about the "elect". For example, Mat 24:22 "Unless those days had been cut short, no life would have been saved; but for the sake of the elect those days will be cut short. (Who is Christ talking about if not believers?) Additionally you must not believe that God chose you for salvation.
There should be no doubt that you are a Christian and one of the elect. Questioning your election is simply questioning your salvation. If you do not know this, then that is a scary thought.