I believe that former Catholics who hate the Catholic Church were not properly Catechized and/or Evangelized. But they will usually believe that they were properly Catechized because they spent 12 years in Catholic School, went to a Catholic College, went to CCD, or were Catholic for many years, etc. They often do not realize the fact that they believe in misunderstandings or myths about the Church or Faith.
My Father is a “former Catholic,” now fundamentalist, who hates the Catholic Church. For example, I was at my parents house, praying the Divine Chaplet (while watching it on EWTN) with my Grandmother (who lives with my parents) and my dad walked in and said to me "don’t come in my house and turn this stuff on; put on ‘Sponge Bob’ for your nephew” (who is only 5). My dad was very rude and had not respect for Divine Chaplet and I’m sure he has never even prayed it (he did the same thing later during the Rosary). My dad had issues with the Church as long as I can remember (from Vatican II to birth control to being able to eat meat on Fridays) and finally “officially left” and got re-baptized over the summer.
I have had numerous talks with him, trying to understand why he was so willing to study the theology of the Baptists, but unwilling to study the real theology & facts about the religion he was leaving.
Same thing with my sister. She was an altar girl, yet still claims that Catholics worship Mary and that purgatory can’t exist because “God doesn’t judge us twice.”
Neither my dad or sister ever spend any time in looking into whether they understand the Catholic Church correctly. They also believe that being a Cafeteria Catholic is what is means to be Catholic and judge Catholics based on the actions of Cafeteria Catholics and the non-Catechized.
Whether they former Catholics become atheist or join another religion (Christian or other); they often do not spend any time seeking the true teachings of the Church. Instead they listen to others and then hate the Church without letting the Church defend itself.
This is why I think we need to do a better job with Child, Teen & Adult Faith Foundation in our parishes. We need to be better are educating our parishioners about the true teachings and what the teachings mean before leave due to misunderstandings.
That’s why I’m personally a strong proponent of having Child Faith Foundation (CCD, CFF, etc) on Sundays, in-between two Mass times. While the children are in CCD/CFF, the Adults can attend a free Adult Faith Foundation session for all Adults and confirmed. Do this weekly. Have guest speakers, such as your parish priests, speakers from the diocese, perhaps the Bishop one week, deacons, nuns, seminarians, a person from Catholic Charities, a Catholic Marriage Counselor or Therapist, Catholic School Principal and/or Theology teacher, Catholic Apologists, etc. You can even keep it short, and start it after donuts & coffee (if you have food, have the food before the session to insure no one eats and then goes to Mass right after).
I’m sure that most (not all, but most) Parishes could pull something like this off.
For example, if you parish has 4 Masses on Sunday mornings, you could do something like this:
7:15 AM Mass
9:15 AM Mass
10:30 AM Faith Foundation
11:45 AM Mass
1:00 PM Mass
7:15 AM Mass
8:45 AM Mass
10:00 AM Faith Foundation
11:30 AM Mass
12:45 PM Mass
Something to think about for all you Priests, Deacons and Religious Directors out there.