Lydia is going to try to change her ways. But she has a longer way to go than most realize, and in real life it would be much harder for her. Gilead used a brainwashing technique called semantic stop-signs, among other linguistic methods. Semantic stop-signs are often referred to as twisted Bible verses. To most, they're a sign that Gilead wasn't actually Christian, but it's more than that. The human brain operates on a linguistic basis. We have a word for everything, and we have trouble understanding concepts that can't be put into words. By controlling the language, Gilead controls our breadth of knowledge and our manner of thinking. They can also put a stop to certain trains of thought. The best example of this is 'Blessed are the meek.' They taught Lydia that obedience and humility were sacred concepts, and whenever the idea of rebellion or talking back came up, she would say that. It was a cognitive leash attached to a collar around her neck, and that is just one example. There were forbidden words--things Gilead wanted erased from the mind. She had a Bible verse for every situation. She was constantly quoting scripture, and it's often pointed out that it's twisted.
All of these techniques dip deep into the soul. They become habit, muscle memory, and cognitive boundaries, beyond which Lydia is incapable of moving. Giving up Gilead for her would be like trying to give up smoking. She's conditioned to think and act a certain way just like smokers are conditioned to pull out a cigarette when they get bored. Their slogans, their beliefs, and all of the old emotions they've embedded inside her could come up involuntarily, like neurons firing out of habit. That's what it means to be indoctrinated for decades. She wouldn't even be able to see the extent of that corruption. She wouldn't know when Gilead was talking. That's why many cult members have to see a therapist. They have a different normal, and they don't know how to find their way back to our own.
Everything in Lydia's being will try to stop her from changing. The brain doesn't like to give up on old habits. It fights back. If she saw something that went against her beliefs--something impossible--she might have a physiological response that causes her to disregard it. If she saw scripture that went against Gilead, the words would scramble in her mind. She might even have trouble reading it aloud. It literally wouldn't make sense to her. If she tried to push past that effect, she would get frustrated or her eyes might get tired. If she did find a way to understand it, she would come up with an explanation that would allow her to believe two contradictory things at once. It might be the most ridiculous explanation in the world; it probably would be, but to her, it would be obvious. A flat earther could be flying in space staring at the globe, and they would still cling to their delusion. It's uncanny. When it comes to belief, our brain will betray us at every turn, especially when those beliefs are attached to emotional stimuli, like the music they play during praise and worship. That's what Lydia is fighting.