You will need to see whether the person is actually following the Qur'an and Sunnah or is he misleading people with his desires. The fact is that, there are many people who are called 'peer' (and this is in the desi countries mainly) yet they are no more than magicians who decieve people with their magic and people consider them to be Awliya and start obeying them in everything. The criterion between those that are true and those that are false is their following of the Sunnah.
Many people fall into error in this question. Once they believe that a certain person is an ally of Allah, they believe that everything an ally of Allah days is accepted, and he is above reproach or criticism in everything he says and does, even though some of that may go against the Qur'an and the Sunnah. Thus, they agree with that person, but go against that with which Allah sent His Prophet (sas) even though Allah has made it obligatory upon the entire creation to believe in all of the information which he imparted, and to obey him in all orders which he transmitted. Allah made him the criterion between His allies and His enemies, between the people of paradise and the people of the fire, and between those content with Allah's decree and the rebellious. Thus, whoever follows him is one of the allies of Allah and a possessor of taqwa (a concept including piety, faith, and righteous practice and action), and is one of the forces who will be successful, and is one or His righteous servants. On the other hand, whoever does not follow the Prophet is one of the enemies of Allah those in loss, the criminals. His opposition and disobedience of the Prophet will push him first of all into innovations (bid'a) and incorrect practice and, in the long run into disbelief (kufr) and hypocrisy (nifaaq).
I suggest you read the entire book of Ibn Taymiyyah, "The Criterion Between the Allies of the Merciful and the Allies of the Devil
" found here:
And of benefit is this thread: