If your parents are not converted, treat them like blind people who cannot see. Spiritually, they cannot see.
What do you do if you see a physically blind man? You don't curse him for stumbling on a stone. You feel sorry for him. Don't you feel sorry when you see a blind man—he doesn't know where to go? Well, look at you parents like that. They don't see the way.
Be kind to them and be merciful, and don't get impatient. You don't get impatient with blind people on the street. Don't get impatient with your parents. Help them.