How do you know what a divine authority has mandated or that a divine authority even exists?
..through study.
I don't agree with extremes.
I feel that the OT is not totally reliable, as it contains ancient texts.
Perhaps that is because I discovered a more recent "version" i.e. Qur'an
The NT is a canon chosen by a particular group of "Christians", in which I find the synoptic Gospels most useful.
They are concerned about the ministry of Jesus and his sayings.
..and then we have 100's of thousands of hadith, which have less authority than the Qur'an,
but can be enlightening, nevertheless.
That's the basics for me,
For example, I don't take the cutting off hands to extreme. It is mentioned in the Qur'an,
so fully accept it. However, I consider such punishment as a last resort, for a "career criminal"
who is of sound mind. I also believe in capital punishment on the same basis.
It would be hoped that such punishment would deter people from serious crime, but I appreciate there is a danger of corruption, where the state can misuse its power.
Most Muslims I come across seem to think that democracy, at least in its western form, is not Islamic.
I disagree. I believe in democracy. I don't agree with presidents who insist on holding govt, despite their subjects disapproval.