Perhaps not but even from a Reformed viewpoint (which I don't share) *we* do not know who the elect are. I'm burdened for this young man (three of my kids are older than he is).
It seems to me that your friend has not been revolutionized by the Holy Spirit...to use Jesus' own words, Born Again. When a person is born of the Spirit, the Holy Spirit literally indwells the believer and entertaining another "religion" is really not an option. Your friend has to go in through the gate first. John Bunyon in Pilgrim's Progress illustrated this perfectly by having Christian and several companions go to the gate. Others found an easier way to go -- a shorter way -- and though they professed great interest and belief in the King and the Celestial City they chose another route.
Your friend has to go through the gate first, and this problem won't even exist. Christianity, as I know you know, isn't just a tag game...it's a literal turn around by the Spirit in our lives.
Prayers going up in gratitude for your faithful witness and for this confused young man. May God open his eyes to the Truth.