Islam cannot be divided into immutable matters and variables
Question

                Is it possible to divide Islam into immutable matters and variables?
Praise be to Allah. 
, and blessings and peace be upon 
          the Messenger of Allaah, his family and companions, and those who follow 
          him.
 
          Recently we have started to hear people saying that Islam 
          can be divided into immutable matters and variables. But as far as we 
          know these phrases were never used by any of the scholars, because the 
          religion of Allaah is all immutable. The Messenger of Allaah SAWS (peace 
          and blessings of Allaah be upon him) did not die until Allaah had completed 
          the religion through him  and had established the rulings. So it 
          cannot be altered or changed until Allaah inherits the earth and everyone 
          on it. No one after the Prophet SAWS (peace and blessings of Allaah 
          be upon him) has the authority to alter or change anything. Allaah says 
          (interpretation of the meaning):
 
          “This day, I have perfected your religion for you, 
          completed My Favour upon you, and have chosen for you Islam as your 
          religion”
 
          [al-Maa’idah 5:3]
 
          The religion, with its concessions and definitive rulings, 
          has been established and after the death of the Prophet SAWS (peace 
          and blessings of Allaah be upon him) it cannot be altered; nothing can 
          be added or taken away: 
 
          “Falsehood cannot come to it from before it or behind 
          it, (it is) sent down by the All-Wise, Worthy of all praise (Allaah)”
 
          [Fussilat 41:42 – interpretation of the meaning]
 
          These words – immutable matters and variables – which 
          trip off the tongues of some seekers of knowledge may be abused by those 
          who follow their whims and desires who may try to change some rulings 
          which do not suit their wishes and desires.  Allaah says concerning 
          this (interpretation of the meaning): 
 
          “And if the truth had been in accordance with their 
          desires, verily, the heavens and the earth, and whosoever is therein 
          would have been corrupted!”
 
          [al-Mu’minoon 21:71]
 
          If these words which some students say may be interpreted 
          in any correct way, they would mean the ijtihaad of the scholars with 
          regard to matters concerning which no text has been narrated. For the 
          opinion of the mujtahid may change from time to time, according to the 
          evidence that is available to him and depending on the circumstances. 
          ‘Umar (may Allaah be pleased with him) said, when his ijtihaad differed 
          concerning matters of inheritance, “At that time, that was our decision, 
          and this time this is our decision.” The ijtihaad of the mujtahid is 
          no more than his opinion, which cannot be said to be the ruling of Allaah; 
          rather it may coincide with the ruling of Allaah or it may go against 
          it. The opinion of everyone except the Messenger of Allaah SAWS (peace 
          and blessings of Allaah be upon him) may be accepted or rejected. The 
          opinions of the mujtahids cannot be divided into immutable matters and 
          variables because they are all open to being changed if it is proven 
          that they go against sound evidence. But the rulings of Allaah and His 
          religion cannot be changed or altered. So the seekers of knowledge must 
          be cautious in their speech and not say anything which opens the way 
          for those who follow their whims and desires and who promote false arguments, 
          because they (seekers of knowledge) are speaking with the words of the 
          scholars and what they say may be taken as evidence concerning matters 
          of religion. May Allaah grant us all knowledge and help us to do righteous 
          deeds. May Allaah bless our Prophet Muhammad and his family and companions.