Disbelief in the Arabic Language means ‘to conceal’. There is no implication whatsoever in the word which justifies the crimes done towards disbelievers by some people, such as killing, terrorising and manslaughtering. There is no link between the word kufr which means disbelief, and killing.
Disbelief is an action of the mind, as Allah U has says:
﴿قُلْ يَا أَيُّهَا الْكَافِرُونَ (١) لا أَعْبُدُ مَا تَعْبُدُونَ (٢) وَلا أَنْتُمْ عَابِدُونَ مَا أَعْبُدُ (٣) وَلا أَنَا عَابِدٌ مَا عَبَدتُّمْ (٤) وَلا أَنْتُمْ عَابِدُونَ مَا أَعْبُدُ (٥) لَكُمْ دِينُكُمْ وَلِيَ دِينِ (٦)﴾
“Say, “O disbelievers, I do not worship what you worship. Nor are you worshippers of what I worship. Nor will I be a worshipper of what you worship. Nor will you be worshippers of what I worship. For you is your religion, and for me is my religion.” [Surah Al-Kafirun: 1-6]
So, the disbelievers conceal (the belief in Allah), that is my belief and they do not believe in what I believe.
That is the meaning of the word. Therefore, those who label people as disbelievers and practice killing, terrorism and crimes on them and then name themselves as true Muslims are actually not linked to Islam at all! This is because, the word kufr means ‘to conceal’ and not ‘to kill’.
It is important to point out that the opening of Surah Al-Baqarah mentions the characteristics of the believers in three verses, the characteristics of the disbelievers in two verses and the characteristics of the hypocrites in thirteen successive verses. Hence, this big number of verses talking about the hypocrites shows us the great danger of hypocrisy and its effects on the community, religion and the followers of religion. Hypocrisy is a dangerous disease which befalls the community. It is more dangerous than clear open enmity as it is hidden enmity.