I can certainly empathize. My mother has always been a Christian since I was born (she grew up in a moderate church). But, she always used to be a very open and somewhat liberal Christian. I even found her reading books about other religions and even Christian Astrology.
But, 2 years ago, she broke her leg and found herself houseridden for several months and dependent upon other people (which was a very humbling and even humiliating experience for my mother because she's always been a very strong-willed and independent woman). Over time, I noticed she watched televangelists more and more often, and she brought up the topic of the Bible more and more frequently. She even got upset when my dad turned away from certain televangelists.
She got "saved" again (she considered her former faith to be "not strong enough") and became "Born Again". It started off harmless (or so it seemed) but over time, she became more and more obessive over watching Black church programs, trying to push us all into regular church attendance, and became more and more concerned about trying to prove the Bible to be "inerrant". She became more and more child-like in behavior (always wanting to be helped and having a child-like slavish adoration of preachers and her image of God).
She even got offended if someone on TV claimed to not be a Christian, and would get upset if someone questioned whether or not something in the Bible was true. It got more disgusting as my mother became noticably more anti-Catholic and eventually stopped considering them to be Christians. She even started referring to them as if they were not Christians. She would say, "Catholics don't seem to believe the same things Christians do." When I said, "Catholics are Christians", she would frown and say, "I don't know, they seem to worship Mary too much and THE BIBLE never said anything about...." She became more and more obsessed with the Bible and wouldn't believe something if it could not be backed up with some Bible verse.
Long after my mother regain motion, she became increasingly more negative towards non-Christians and seemed to believe there was no depth a non-Christian was incapable of. She even considered Christians who don't believe the Bible to be inerrant "heretics". She also became noticably more homophobic and hateful of anything she considered "sin". She accused me and my siblings of being "possessed" if we ever disobeyed, and would pray and lay hands on my little sister if she had problems waking up for school (she considered having a problem waking up to be a sign of demonic possession

).
Recently, she reached her ultimate low when my dad (who is also becoming a Fundamentalist) didn't agree with her on something in the Bible, and it became an argument about marital problems. She started screaming and saying that she was "unequally yoked" from us and started crying about, "If Jesus, the Son of God was persecuted, I should expect to be too! I just try to be a good Christian, and everyone attacks me! That man [Jesus] was pure sinless GOD!!! He died for everyone and the whole world HATES him! Now everyone HATES me!" then she broke out into a disturbing "Dear Heavenly Father" prayer in front of us.
I eventually got her to calm down (after she called me "Satan" for trying to calm her, she knows I'm a non-Christian) and she just sat there shaking and reading the Bible with a disturbing experession on her face (eyes bucked). Since I've been back at college, I've called home almost every day, and she seems to be mentioning religious issues less and less (she used to try to proseltyze something every single day or get into some sort of religious debate of some sort; sometimes if someone on TV said something to make her question her faith, she would talk to us and try hard to refute their comment with Scripture or Church dogma, as if the person on TV would hear it).
I hope her relaxing of dogma is a sign that her Fundamentalism is subsiding (my siblings used to complain to me all the time how my parents would bother them questions about whether they believed in Christ or if they were going to Heaven almost daily).
I TRULY AND DESPERATELY HOPE MY PARENTS' (ESPECIALLY MY MOTHER'S) FUNDAMENTALISM IS JUST A STAGE LIKE I WENT THROUGH ONCE.I HATE RELIGIOUS FUNDAMENTALISM WITH A PASSION, I HAVE SEEN FIRST-HAND THE KIND OF MENTAL DAMAGE IT DOES TO ITS BELIEVERS, AND IF I HAD MY WAY, I'D BUILD A MACHINE TO DE-PROGRAM EVERY SINGLE FUNDAMENTALIST ON EARTH.