Someone cannot be a part of Islam. Someone can either be or not be a Muslim.
According to Quran, there can be no parts, no different perceptions in Islam. Allah repeatedly disapproves forming parties/sects/groups in religion (see. 3:103, 6:159, 30:32, 42:13) and says that He has given the name “Muslims” to believers:
“(…) He named you Muslims before, and in this (Quran), that the messenger may be a model to you and you be models to others. (…)” (22:78)
A Muslim cannot adopt another name but “Muslim”. Muslims should define themselves the way Allah defines them.
Muslims should also be kind and equitable to all people besides the ones that fight them because of religion, expel them from their homes or aid in their expulsion. Allah says:
“Allah does not forbid you from being kind and equitable to those who do not fight you because of religion and do not expel you from your homes. Indeed, Allah likes those who are equitable. Allah only forbids you from making friends of those who fight you because of religion or expel you from your homes or aid in your expulsion. The ones that make friends of them are the wrongdoers.” (60:8-9)
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