I've always thought that threatening your kids with hellfire or anything else that isn't true like this, is a sure sign that the parents lack any parenting skills whatsoever. This goes for corporal punishment too. The problem is, these guys are not as smart as their kids, so they have to result to something "scarey" to get CONTROL. It backfires later when the kid realizes the parent can't control him/her that way anymore and metaphoricaly gives the parents the finger.

With a rational upbringing the child will grow into adulthood respecting their parents.

Unfortunately, I don't think you can legislate away stupidity. If you outlaw corporal punishment, then they make threats. If you outlaw threats, then they will use something else just as abusive. Therefore: IQ tests for parents!