Ethics & Religion: Mike McManus:

It is never easy to be a parent. But this week parents of 30 million teenagers will find it particularly difficult to deal with their children's craze over Marshall Mathers, better known as the hip-hop sensation, Eminem, (''M & M'').

On Wednesday night the angry, tattooed, foul-mouthed, drug-promoting, gay-bashing, bleached blond, murder-idolizing rapper won three Grammy Awards, for what is arguably the most disgusting album ever made, ''The Marshall Mathers LP.''

What is most disconcerting is that this celebrator of mayhem, whose songs include fantasies about killing his mother and his wife - is worshiped by today's teens. They have snarfed up 8 million copies of his wretched album that glorifies sodomizing his mother and setting up his sister to be gang raped. The odds are nearly one in three that this album is in your house, if you have a teenager. The odds are 100% that your teens have heard his ''music,'' multiple times.

Though I hate to do so, I must quote some lyrics, before suggesting what parents might do about this one man plague on morality. I hasten to add I can barely understand the machine gun patter of rap, and am grateful to Focus on the Family's ''Citizen'' magazine for printing some lyrics, and to Focus' ''Plugged In'' Music Review by Bob Waliszewski.

In ''Amityville,'' Eminem sings, ''My little sister's birthday/She'll remember me/For a gift I had ten of my boys take her virginity.'' Will this not encourage simple minded brothers to imitate their idol's suggestions to rape their sisters?

In ''Bonnie and Clyde'' your kids hear, ''...don't worry/Dada made a nice bed for Mommy at the bottom of the lake. Here, you wanna help Dada tie a rope around this rock?/We'll tie it to her footsie, then we'll roll her off the dock. Ready now, here we go on the count of three.../One, two, three, whee! There goes Mama, splashin in the water/No more fightin' with Dad, no more restraining order.''

This is moral poison, whose impact is incalculable. It is a depth charge to the culture, an incitement of horrific matricide. No real deaths have yet been attributed to Eminem, but I fear it is only a matter of time. In fact, his own mother has sued her son for $10 million for defamation of character.

Eminem mocks his own influence in the song, ''role model.'' ''Follow me and do exactly what the song says: Smoke weed, take pills, drop outta school, kill people and drink/And jump behind the wheel like it was still legal...''

Marshall Mathers was born to a 17-year-old. He never saw his Dad. ''By age 9, the undersized boy had attended five elementary schools in four cities and faced a host of playground assailants. He was beaten...unconscous; he was beaten into a 10-day coma... that reportedly took a dozen doctors and a half-million in medical bills,'' reports ''Citizen.'' He dropped out of school after flunking 9h grade twice. His uncle who introduced him to rap committed suicide and he saw another uncle shoot and kill his brother-in-law.

Tattooed on his belly is a tribute to his childhood sweetheart and wife, Kim: KIM - ROT IN PIECES. She has inspired two songs involving his apparent murder of her. In one we are treated to the gurgling sounds of Kim's throat being sliced. He allegedly inspired Kim to attempt suicide.

What can be done? First, most parents have to realize they are partly responsible for inviting this misanthrope into their children's lives. Fully 60 percent of teens have their own TVs in their bedrooms. Why? What does that add to your child's life? The sewer of MTV that brings Eminem and his competitors for free to pollute the minds of your children.

I suggest that you sit in their bedroom one evening and watch this hideous trash with them. If your kids have Eminem's albums, listen to them. Enter into your kids' entertainment world. Learn what they are seeing and hearing.

Then, when you have evidence, make some new rules. Throw away Eminem's seductive siren song to sin. Unplug your kid's TV and put it in the attic.

When the outraged protests erupt, offer an important olive branch. Invite to take your son or daughter to a great vacation spot on their next birthday, just you and that teen or pre-teen, alone. I did this with my sons when they turned 13. It was wonderful.