You ask a very challenging question that all of us should think on ... and i will continue to think on.
Initially i can explain say this though, although i am only speaking for myself.
Personally, i do not mindlessly accept everything ANYONE tells me. I evaluate EVERYTHING against logic, reason, balance, and what ALL of the Bible says, not just one or two verses or parts of verses. I ALWAYS use the attitude "show me" with EVERYONE ... although i do agree with you that far to many people don't, regardless of a person's belief systems. But i will admit that i became that way only when i had been betrayed by several pastors/teachers and knew that there was only one Person that i could truly trust, and that was Jesus Christ Himself.
* If you will allow me to go to your third question before your second, i am 60 years old at this point so i have gone through enough of life to have had my faith/trust in Jesus Christ to have been proven countless times. And the older i get and the more struggles that i face because of my increased struggles, the more He proves my trust in Him.
* To answer your second question, i heard someone answer this same question this way. "If atheism is right and Christianity is wrong, i don't lose anything ... and in fact have lived the best life that a person can live, living honestly and helping people in every way that i can. But if Christianity is right and atheism is wrong, then that person loses everything." And this sounds like a reasonable explanation although it does feed back into your "show me" critique ... which for me is not the case ........ and it also makes the unreasonable assumption that atheists/etc. don't live honestly and kindly and givingly because that is dramatically and decidedly untrue ----- because, as you have said yourself, i have seen Christians do some of the cruelest and most unconscionable things using God, the Scriptures, and Jesus Christ as justification and rationalisation --- including to me. And i eventually had to decide that i would be a Christian because i was a follower and obeyer of Jesus, not because of any Christian ~~~ which leads me back to #1. And the pastors/teachers that i love and trust the most are those that agree that i should be putting my obedience to Jesus Christ FAR above any belief i'd have in them.
* Would you be interested in checking into something? There is an author that i know about and deeply respect who might be able to answer your questions. He was an atheist investigative reporter who set out to prove that Christianity was a lie ..... only to prove just the opposite and accepted Jesus Christ as his Savior himself. His name is Lee Strobel; he has a website and many books, the first being "A Case for Christ". He is one of the VERY FEW people and Christians that i respect ... and from what you've shared, perhaps it might help answer some of your own questions. There is also a book that has helped me with some of the things Christians have done to me that perhaps might help you, too; "The Subtle Power of Spiritual Abuse", by David Johnson and Jeff VanVonderen.
I will continue to think on your question, because it is a good one that challenges.
I hope the thoughts that i have shared are something that you can use, too.
I will be keeping you in my thoughts, Lyn (and, if you will permit, my prayers ---- i've had some of my non-Christian friends laugh and tell me, "it certainly can't hurt" :-D LOL).
PS: Thank you for sharing your past, Lyn; it helped me to know how to answer your question. Unless i know otherwise, i usually guess that the person that i am answering is unfamiliar with the Bible and Christian beliefs. But, yes, there are many times i am ashamed to admit that i am a Christian because of what i see so many Christians doing ... finally only being able to continue to be a Christian by deciding that the reason i was a Christian was because of Christ, not because of other Christians. I don't know if you'd be interested, but there are two Christians that i very deeply respect because of the loving way they treat people and live. Both of them have websites so i believe that you should be able to pull them up no matter where you live; Dr. Mark L. Walker, head pastor of Mount Paran North Church of God in Marietta, Georgia, United States (one of my former pastors) and Max Lucado, a pastor and prolific author, maybe starting with his book, "When God Whispers Your Name".
Another resouce that i think you might be interested in checking out is New Life Ministries; they have a website, too. One of the books that they offer, too, is one having to do with the damaging things Christians do; i haven't read that book, but i know NLM and can suggest it based on my knowledge of them.
You take care of yourself, Lyn, okay?
You will be in my thoughts.