I think we both have the same understanding of the main point of the whole paragraph.
But I think ‘think away’ means ‘avoid some thoughts by thinking’ or ‘avoid some thoughts by thinking other things’
That’s why I take ‘think away’ as ‘not to think’ though there are subtle differences in the meaning.
So i would transform these words into:
Cannot think it away->have to think it
Without thinking away -> With the thought of
Here is my understanding of the sentence:
We have to think it (the conviction that we are free beings) with the thought of having much of our fundamental sense of humanity. This sense is so much that the attempt (Kant’s framework) is impossible.
That’s what i come up with this morning. I actually kept thinking about it for a night