Your friend’s response saddens me. Don’t judge Calvinism based on his half-baked answer. I wish I had time to get into this discussion now, but all I have time to say is that I lacked real assurance until I understood and accepted the Doctrines of Grace. Next to being saved, that understanding was the best thing that ever happened to me.
How do you know that your “assurance” is truly real? Can one’s own heart deceive them?