Hi
I'm responding to this, but I am not autistic - though my nephew and niece are, so I have people I love who will deal with the very things you are. I am responding because my struggle was similar but different. Sometimes I've found it can help to try and see a similar issue for a different perspective.
I became a Christian when I was 14, but left the Church when I was 19. I threw away almost everything connected to Church, cut off Christian friends, and started over. I did that asking the very same question you are asking. How could God create me this way? And yes, there was bullying, and endless well-meaning Christians giving me "advice".
I know this may being me issues in being so open, but I stopped living a double life a long time ago now. This was my problem: I'm gay.
I desperately wanted nothing more than to be straight. I prayed, cried myself to sleep most nights, and begged God to cure me or let me die. And I meant that. I'd have killed myself if suicide wasn't a sin! I thank God now that he didn't answer that prayer!
I used to ask God, "how can you create me like this, and then tell me I can never fall in love?". "How can you ask me to spend my life alone?" Lots of Christians used to say, "but you are not alone, you have Jesus". Very nice when most of them were wearing wedding bands. Clearly not enough for them! They clearly meant well, but they had no idea of the hell I was living through.
Being gay is also largely genetic, and a result of the fall. I definitely didn't choose this. So the questions I had were similar. 8 years later I came back to faith, and have now reconciled my faith and sexuality (not for discussion here). Here is what I have learned, I hope some of it will translate to your situation.
A lot of the issues we can have are made more difficult because the communities we live in don't understand what we are dealing with. It's too easy to simplify things for them because they are not living the experience. For them it's either theoretical or theological, for us it's our very lives.
As a result of all of this, we start to reject ourselves based on an "ideal" that really doesn't exist. The ideal is Jesus, and none of us match up to that! We are all defective because of the fall. For me it's being gay, for you it's autism. For others its illness, addictions, you name it - everyone has issues. But before we start rejecting ourselves we need to be honest. Is this my fault? Can I change it? Addictions can be overcome (even if it takes our whole life). Illness maybe not. But denying you are ill won't help. Such a person needs to accept the diagnosis and accept the treatment, right? I guess what I am saying is that if you don't accept who you are, you're not going to move forward.
Whether it's being gay or autistic, we didn't choose this. It's just part of who we are. So it isn't something you can reject.
Jesus said "you will know the truth, and the truth will set you free" (John 8:32 NIV). There are two ways you (and I mean YOU) should take this statement.
The first is knowing the truth about yourself. You are autistic, but you are so much more than that. It's part of who you are, but it's not who you are. It's not the most important thing about you. I am a Christian man who happens to be gay. You are a Christian man who happens to be autistic. I hope that makes sense! Because it's innate, fighting it or rejecting it isn't setting you free is it? It's probably making things worse for you, right? Why? Because, as Jesus said, the TRUTH will set you free. So accepting it sets you free. From there you can start dealing with the "how do I live with this" questions. You do not have to accept the bullying, the humiliation etc. You are a human being, a beloved son of God. THAT is first and foremost who you are.
The other way to take this is that Jesus said he IS the truth - and he can set you free.
Jesus knew who you are when he chose to die for you. You have immense value to God - he loves you and accepts you - and he knows the struggles you are facing.
Autism brings it's own unique challenges, and you have a role in educating your communities about what it means for you, how they can help you, and I hope that they accept you.
I hope that some of this is helpful. I'll be praying for you brother.