old argument that "If God exists, why does He let bad things happen?" The oldest atheistic argument in the books.
Bad things happen because of Original Sin and Free Will....I'm sure you've heard the rest (though I do believe that you really didn't understand it or that it was not explained well to you at the time).
The neuro surgeon cannot explain it and had tears in his eyes after seeing it. I have seen the same in my life - both private and professional. I don't feel like I need to see those miracles, but they are all around for those who don't want to believe. God calls you back.
I have no intent to push you farther away, but you are making a choice not to believe the obvious. I hope that someday, you change your mind.