"You may not know this, but Jewish parents traditionally have gone into mourning when their children converted from Judaism to Christianity because to them it was like losing a child."
What you say is true but I wonder how they'd feel when they really lose their child to war or death of another means. This kind of attitude really minimizes true loss and is an insult to anyone who has lost a child (reality) vs. these emotional dramatics.
Who are you to decide anything for anyone Jewish? Leaving one's faith or culture does make some parents go into mourning. I suppose you'd have a BBQ and kegger if one of your kids announced he or she was going Hare Krishna?