Are your parents open to a discussion so you can rebut the anti-Catholic sentiments? If so, the tracts here on CAF are great. You may ask, “Mom, do you agree with Pastor X about Purgatory? If so, why?”
If they’re not open to a dialogue, I would politely busy myself with something else.
Or, perhaps, if you are driving your mom or dad in your car, you could play an MP3 of Catholic Anwers Live Open Line burned onto a CD or through an MP3 player. Or, if you’re in the kitchen making dinner, cleaning the car in the driveway, or just doing laundry, have it playing on portable CD or MP3 player at a moderate volume.
You can even get Father Groeschel’s tapes at a decent price…or they may even be available at your local library.
I would also leave books like “Catholic Answers to Fundamentalists Questions” or “The Catholic Answers Book,” Vols 1, 2, or 3 around. However, I wouldn’t start putting up icons all over the place, other than your room.
There is a line of respect that you shouldn’t work overtly to make your parents uncomfortable in their own home. The key is, if you’re up to evangelizing, first do it through your behavior and second by being open to any questions they may have. Lead them to water, as it were…
How about playing a CD of the rosary or tuning the main TV to EWTN when you get the chance? (But don’t do it with a rebellious spirit, and let them change it if they want.) Remember, if they’re not listening to what’s being said on TV, they’re probably going to ask you why YOU are listening!
Also, if you play the Rosary or hymns, you should brush up on your apologetics, because they may ask you something and they may expect you to have the answer on the spot. That can be tough.
Overall, be serene. Your parents home is not a place to battle. If they’re not open to anything of the Catholic faith, commend them to the Holy Spirit and agree to disagree…and keep them in your prayers always!
PS I didn’t mean to sound harsh in any way – I’m just speaking from experience.