In case of Quran since it claims there is a casting from Iblis pertaining to it and that hard hearts follow what he casts, and that results in people taking words of God way out of their place (contextualization does not happen), it would prove it false.
So doesn't that suggest that your first point is assuming the answer, since the alternative answer is 'The Quran is false'?
You are only chasing down one of the two possible responses to your first point.
If you chase them both down, you are left with 'Either the Quran is true, or it is false.'
Which we can universally agree with.