Why are you despairing in your patient's condition of nominal Christian? This indeed can be harmful but it also allows for uniquely diabolical manipulation. Being raised in the church, (especially those being run to Our Father's satisfaction) means that she has a cursory and vague overview of the bible. With that seed already sown your job is to make her embarrassed of her knowledge and shameful of what that book says. This is difficult if they know it well, but those who know only parts can be goaded into shame. And as you know Shame is one of our most powerful weapons. It makes the humans cowardly which makes them more shameful and so on. They can almost be eaten alive!
Another great thing about those who left the church with this base knowledge is that they think themselves wise while knowing very little. Then you can get them to speak with great rhetoric on why they rejected something quite other than true Enemy-worship. And as long as their hearers are slightly more ignorant than they, we will have great success.
Remember Snakelips, it's all about getting them to have a bad first taste so that they dread ever taking another bite.
Affectionately,
Screwtape
