The word(s) "disbelieve" appears 631 time(s) in 561 verse(s) in Quran in Mohsin Khan translation.

(421) And those who disbelieve will say: "Our Lord! Show us those among jinn and men who led us astray: that we may crush them under our feet so that they become the lowest."

(422) Verily, those who turn away from Our Ayat (proofs, evidence, verses, lessons, signs, revelations, etc. by attacking, distorting and denying them) are not hidden from Us. Is he who is cast into the Fire better or he who comes secure on the Day of Resurrection? Do what you will. Verily He is All-Seer of what you do (this is a severe threat to the disbelievers ).

(423) Verily, those who disbelieved in the Reminder (i.e. the Qur'an) when it came to them (shall receive the punishment). And verily, it is an honourable well-fortified respected Book (because it is Allah's Speech, and He has protected it from corruption. (See V.15:9)

(424) And if We had sent this as a Qur'an in a foreign language (other than Arabic), they would have said: "Why are not its verses explained in detail (in our language)? What! (A Book) not in Arabic and (the Messenger) an Arab?" Say: "It is for those who believe, a guide and a healing. And as for those who disbelieve, there is heaviness (deafness) in their ears, and it (the Qur'an) is blindness for them. They are those who are called from a place far away (so they neither listen nor understand)."

(425) Man (the disbeliever) does not get tired of asking good (things from Allah); but if an evil touches him, then he gives up all hope and is lost in despair.

(426) And truly, if We give him a taste of mercy from Us, after some adversity (severe poverty or disease, etc.) has touched him, he is sure to say: "This is due to my (merit); I think not that the Hour will be established. But if I am brought back to my Lord, surely, there will be for me the best (wealth) with Him. Then, We verily, will show to the disbelievers what they have done, and We shall make them taste a severe torment.

(427) Say: "Tell me, if it (the Qur'an) is from Allah, and you disbelieve in it? Who is more astray than one who is in opposition far away (from Allah's Right Path and His obedience).

(428) And thus We have revealed to you (O Muhammad صلى الله عليه و سلم) a Qur'an in Arabic that you may warn the Mother of the Towns (Makkah) and all around it, and warn (them) of the Day of Assembling of which there is no doubt: when a party will be in Paradise (those who believed in Allah and followed what Allah's Messenger صلى الله عليه و سلم brought them) and a party in the blazing Fire (Hell) (those who disbelieved in Allah and followed not what Allah's Messenger صلى الله عليه و سلم brought them).

(429) And He answers (the invocation of) those who believe (in the Oneness of Allah - Islamic Monotheism) and do righteous good deeds, and gives them increase of His Bounty. And as for the disbelievers, theirs will be a severe torment.

(430) And you will see them brought forward to it (Hell) made humble by disgrace, (and) looking with stealthy glance. And those who believe will say: "Verily, the losers are they who lose themselves and their families on the Day of Resurrection. Verily, the Zalimun [i.e. Al-Kafirun (disbelievers in Allah, in His Oneness and in His Messenger صلى الله عليه و سلم, polytheists, wrong-doers)] will be in a lasting torment. (Tafsir At-Tabari).