Why did Allah the Exalted give human beings an Intellect and the faculty of Reason? Is Reason and Intellect the perfect guide?
Many things in the Sharia of Sunni Islam, make sense to Reason, other things make no sense at all. Muslims are taught to use their Intellect with regard to Knowledge it can master and apprehend, and in areas where it is blind, it must submit to the Sharia.
The Sharia as a whole when examined by the Intellect can only see goodness in the Laws and a source of benefit for all Creatures, human and non human, individuals as well as societies. It is from Allah, by Allah, to Allah. When examined in detail we notice some things the intellect cannot grasp, for instance the most famous example is the Wudu (ritual ablutions Muslims perform daily), the last act is to wash the feet three times. However the Sharia ruling is that if someone is wearing leather socks, they only need to wipe the top of the sock with wet hands for the Wudu to be valid. Rationally this makes no sense, as dirt accumulates at the bottom of the sock, yet we are being asked to wipe the top. In such cases the Muslim submits and declares ‘we hear and we obey’.
This is not some irrational tendency because we have already examined the whole of the Sharia with the Intellect and worked out that it is good for all. That some details may not make sense to some Intellects is purposefully placed in the Sharia by Allah the Exalted in order to make man submit his Intellect to Allah. Allah knows Best, He is the Most Wise.