These couple of points I'm going to bring are my personal beliefs from studying the bible and from life experiences. I'm just bringing this here to provide another look at this matter. I also didn't read the whole thread, so if I'm repeating stuff, I'm sorry. I ask that you be open minded and think about it honestly. Also, English isn't my main language so sorry if there's any mistake
1. There's a couple ways that "all knowing" can be interpreted. You could say that God just know everything, that He knows everything you are going to be tomorrow, every choice you will make, every thought you will think and every felling you will feel. I don't think it's like that, because then you reach problems like what is being asked about in the OP. In my view, God knows every possibility. Like, if you come to a fork in a road, he know what will happen if go left, if you go right, if you go back, if you just stand there, if you suddenly started dancing, if you kill yourself, if you sleep, etc. He knows the possibles moves that every particle in the universe can make, what what will result from them.
The thing is that you can see the universe and it's laws as a system. He made the system to work for him (And obviously can interfere with everything, so if he wants one of the various possibilities to happen he can make that happen). For example, let's say I have a bunch of MP3 on my computer and I want to pass them to my phone. I can go to the folder and copy the MP3 and them paste on the phone, or drag and drop, whatever. But being a programmer I can make a code that every time I connect my phone on the PC, it grabs every file that has been modified since the last time I plugged my phone and copy them to the phone. Similarly, God created systems that work for him. Why make a bunch of planet by yourself when you can make a system that generate them randomly? You could ask "God could just snap his fingers and every planed appears on their location, fully functioning. Why would he make a system to do that?". If you think about, for example, photosynthesis, it is a system that maintains plants living, instead of God doing that. (And I feel I'm really not explaining this well, so just imagine a system that would completely substitute God manually doing it.)
That way we have free will. We have choices. The world is the way it is, because we made choices that lead to this. The systems are working on their own. People die in natural disasters because the system works, and it's just doing what it's programmed to do. It reads the variables we altered and just output the results. Now, where does Christianity fit into this? God gives as a choice of turning to him and to make a relationship with him. And since he has an ideal of what a person should be and do, he works in us to make us more like that, because we chose. He knows the outcomes and he can instruct and help you reach the ideal outcome. And ANYONE can receive it was well, they just have to want it and commit to it.
2. Now, to the question itself, you can say is both "What doesn't kill you makes you stronger" and "There's three types of people: The ones who learn with the mistakes of others, the ones who makes an mistake and learn with it, and the ones who keep repeating the same mistake over and over". For the first one, the troubles you might face even if you're following God it's about molding you, making you stronger. Sometimes (and depending on the people) having you experience something first hand is the best way to make someone grow. For example, I am an introvert so I'm attached to very few people and I don't view death as something extraordinary. I don't feel the need to mourn or to feel sad that someone died as it's something that happens naturally. Everyone will die someday (Of course have your life taken against your will is another story). I experienced 2 deaths in my family, both grandfathers who I wasn't close with. But one day, I might lose someone very important and that might change my views on death. Or maybe not. But it's definitively something that only going trough it could change me.
For the second one, the first type, that learns with others mistakes, that's what the Bible is for. the bible is NOT a manual, a Life 101. It's there to provide experiences, to make you think. There are many types of people in the world, with different needs, different abilities, different problems. So the bible is not direct (The only things it IS direct, it's when it's universal, like "Don't kill people") because of this. You have to interpret and see what applies most to you and work with that (That's not "pick what you want"). For example I struggle most with pride, and due to my introversion I really don't have much problems going against social norms. I don't drink and never felt compelled to. It's pretty easy for me to not abuse that (at least right now), so I can disregard most of stuff about this because it comes naturally, but the things that I do have trouble, like I said, pride, that's is what I should focus on. And someone might have the complete opposite of me, so the stuff that would be useful to me in the Bible, might not be useful at all to them. The second type of person, is the "makes you stronger" I mentioned earlier, The last type, is why Christians want to share their world view. To us, some stuff you might be doing can be considered as an mistake, and we don't want to see you repeating that.
This is too long already so I'm going to cut it here. I could keep going, and be more detailed, explaining some nuances and whatnot, but I'm not in the mood. I hope I could shed some light on this for you guys, and I sincerely hope that this might've changed your views on Christianity. I see a lot of people assuming stuff about it and they all talk like they know everything about it while in reality they don't. These stuff you only understand by studying and living trough these lenses.