A disbeliever is an atheist, or one who states with his tongue “I do not believe in God or his prophets”. One must have the CORRECT KNOWLEDGE of Islam and reject it to earn such a derogatory name.
Unfortunately, you will find Muslims who are knowledgeable and some not who will call someone kufur or kafir and feel no remorse. This is not of the sunnah of the Rasul (saw). (Perhaps one should question whether or not they are kafir, when they are so quick to call another such name). In other countries it is noted blacks (African decent) were/are called Kafirs and still to this day this niggardly behavior is practiced (racism) amongst the Muslims, but is NOT a practice of the Diin of Islam .
From this, One who has respect for mankind no matter his/her religion, treat people in the proper way, he must not be considered a kafir, also because it cannot be said that he has got correct knowledge of Islam.
Takfir (declaring apostasy) is not an easy affair. Just like any ruling it has certain conditions that, if not present, will prevent the ruling, in this case disbelief, from occurring. (n Islamic law, takfir or takfeer (تكفير) refers to the practice of one Muslim declaring another Muslim an unbeliever or kafir (pl. kuffār). The act which precipitates takfir is termed the mukaffir.)
Here are some of those conditions:
- Declaring apostasy cannot be based on probability, meaning if there is a chance that a person may not be a kafir. Imam Malik said, “If I have 99 reasons to believe a person is a kafir and one to believe he is not, I’ll prefer the latter.”
- Takfir is made regarding things that are known by default, like God being one and the finality of prophethood. The Malikis listed 33 issues that fall under the heading, malum min al-din bi al-Dururrah.
- Takfir cannot be based on following an opinion (ijtihad) of a scholar in fiqh (legal verdict). There is not a kafir in fiqhbecause fiqh implies knowledge of things beyond the average person’s scope. For that reason a person is not declared a kafir who makes tawassul (praying to Allah through an intermediary). Imam Ahmed said, “We do not declare such people as kuffar.”
- Takfir cannot be based on a sincere attempt to interpret or understand a text. Allah subhanahu wa ta`la (Exalted is He) mentions the followers of Christ saying, “Can God send a table from the heavens?” This is a statement of kufur but they were excused because it was a sincere question and an effort to understand.
- Takfir cannot be based on actions that are due to ignorance. In the Qur’an we find the followers of Musa alayhi assalam saying, “Make for us idols to worship like they (the people of Egypt) had.” Musa’s response was, “You are an ignorant people.” He did not say that you are a kuffar. This verse servers as the foundation for the axiom “Al-’Uthru bi Jahl” (Ignorance is excused).
- Takfir can only be made on an act of pure worship coupled with an intention that is clear kufur. Al-Dhahabi said, “If I saw a Muslim making sujud to a grave, I would not declare takfir until I talked to him.”
- Takfir cannot be made upon an action that was done under the threat of harm. Allah (swt) says, “Except for the one who was forced (to say kufur) and his heart was full of faith.”
- Takfir cannot be made upon an act that was an emotional burst. The Prophet ﷺ (peace be upon him) said that the man who lost his camel in the desert and later found it, said, “God! You are my servant and I am your Lord.” The Prophet ﷺ did not say this man was a kafir even though the statement is kufur. Ibn Hajar notes that this man was overcome with joy, so his statement was an abbreviation.
- Just because someone’s group is not from Ahl-Sunna does not mean they are kafir. For that reason the companions prayed janazah (funeral prayer) for the khawarij. They did not collect the spoils of war from them, but gave it to the deceased’s family according to the Islamic rules on inheritance. Ibn Taymiyya says that this proves the companions considered them Muslims