I really liked this article and I thank the poster for posting it. Brothers, if you read the article, you will notice it mentioned how the Qur'an never tells us to call non-Muslims as "kaafir". But He, Allah, does in the Qur'an because is the All-Knowing; whereas we are not. So we should refrain from this because of two reasons:
1) We do not know the taqdeer of others, this person who we call kaafir might one day become a Muslim, or he might not when he remembers how intolerant Muslims were to him by calling him kaafir.
2) Even though in Arabic, kaafir means "one who does not believe" or "one who denies the truth" (as in the Qur'an), it has become an insult and a derogatory term (like other members pointed out) that Muslims use against non-Muslims.
Also, as mentioned in the article when referring to Surah Al-Kaafiroon, the Surah ends in a beautiful way.
Sahih International
"For you is your religion, and for me is my religion."
1) We do not know the taqdeer of others, this person who we call kaafir might one day become a Muslim, or he might not when he remembers how intolerant Muslims were to him by calling him kaafir.
2) Even though in Arabic, kaafir means "one who does not believe" or "one who denies the truth" (as in the Qur'an), it has become an insult and a derogatory term (like other members pointed out) that Muslims use against non-Muslims.
Also, as mentioned in the article when referring to Surah Al-Kaafiroon, the Surah ends in a beautiful way.
Sahih International
"For you is your religion, and for me is my religion."
And finally, the disrespect shown to a dead person by calling him kafir is also against the Prophets own beliefs. Once he saw the cortege of a Jew pass by. Immediately, he stood in honour of the dead person. When a companion reminded him that it was a Jews cortege, the Prophet shot back: Was he not a human being?