Shaykh-ul-Islaam Ibn Taymiyyah (rahimahullaah) was asked:
Regarding the Prophet’s statement: “Anyone who possesses a speck of pride (kibr) in his heart will not enter Paradise” – Is this hadeeth specific only to the believers or (is it specific only to the) unbelievers? If we were to say that it is specific for the Believers then (is not) our statement trivial considering (the fact that) the believers shall enter Paradise due to their Eemaan. If, on the other hand, we were to say that the hadeeth is specific for the unbelievers then what is the relevance of the statement (since it is already known that the unbelievers shall not gain admission to Paradise?
He (rahimahullaah) answered:
(Another) authentically reported wording of (this particular version of the) hadeeth is, “Anyone who possesses half a mustard seed of Pride (kibr) in his heart will not be granted admission to Paradise. And anyone who possesses half a mustard seed of Eemaan will not enter the (Eternal) Fire.” 
Kibr that openly opposes and negates Eemaan results in the banishment of the one who holds it from entering al-Jannah as is found in Allaah’s statement:
“And your Lord said: "Invoke Me, I will respond to your (invocation). Verily! Those who scorn (yastakbiroon – Have kibr) My worship, they will surely enter Hell in humiliation!" [Surah Ghaafir: 60]
This is the Kibr of Iblees (the Devil), Pharaoh and all the others who possessed the Kibr, which invalidated Eemaan. This is also the Kibr that the Jews possess and those whom Allaah has described to us by saying:
“Is it that whenever there came to you a Messenger with what you yourselves desired not, you grew arrogant? Some, you disbelieved and some, you killed.” [Surah Al-Baqarah: 87]
Al-Kibr, in its entirety, openly opposes the essentials of al-Eemaan. As such he who has an atom’s weight of Kibr in his heart will not act upon that which Allaah has prescribed, nor will he abstain from that which Allaah has prohibited. Instead his Kibr shall result in his disavowal and rejection of the truth and instill in him contempt of others. This, precisely, is the explanatory definition of al-Kibr provide by the Prophet as is found in the complete version of the initial Hadeeth [“The one who possesses an atom’s weight of Kibr in his heart shall not be granted admission to Paradise.”]
He (sallAllaahu ‘alayhi wa sallam) was asked: “[But] O Messenger of Allaah! A man likes to have fine clothing and footwear. Is this included in Kibr?” He responded, “No. Allaah is Beauty and loves Beauty. Kibr is the rejection of truth (Batrul-Haqq) and condescension of others (waa ghaamtun-naas).” 
The statement “Batarul-Haqq” denotes distain and rejection of the Truth, while “ghaamtun-naas” implies contempt and condescension of others from amongst mankind.
Therefore the one who possesses half a mustard seed of it (Kibr) rejects the Truth that he was ordered to accept and act upon. At the same time, the Kibr instills in him a sense of condescension that inculcates in the individual an oppressive demeanor producing transgression over the rights of others.
The one who neglects his obligations (due to his rejection of them) and is oppressive to others from amongst the creation is not to be amongst the people of Jannah (while in this state), or deserving of it. On the contrary, such an individual is to be counted amongst the people who are threatened with punishment!
His (sallAllaahu ‘alayhi wa sallam) statement: “Anyone who possesses a speck of Kibr in his heart will not be granted admission to Paradise” implies that the individual is not from the people of Jannah and is not deserving of it. But if he repents, or he possesses Hasaanaat (righteous deeds) that expiate his sins, or Allaah has given him Ibtillaah (trials and tests) in the form of calamities that have expunged his sins, or similar things; then for that individual the recompense of Kibr – which originally was a barrier for him to enter Jannah – is eliminated and he gains admission (to it). Similarly Allaah, due to Divine Grace, may forgive the individual (the sin of) Kibr.  None shall gain admission (to Paradise) while possessing an atom’s weight of Kibr. As a result, those (scholars) discussing this Hadeeth, and other Hadeeth that have a similar theme, have stated:
“Unconditional admission (to Paradise) – that is not in conjunction with punishment (for the sin of Kibr) – is what is being negated in this Hadeeth; not the admission to Jannah that is granted to those who have entered the Fire (to be purified and cleansed) and then are allowed admission to Paradise thereafter. (On the other hand) if a hadeeth explicitly declares that a particular person is in Jannah or that a particular person is from the People of Jannah, it would then be understood that he would enter the Jannah and not enter the fire (beforehand).”
After this clarification we come to understand the true meaning of these narrations as being that the one who possesses an atom’s weight of Kibr in his heart is not from the people of Paradise (up to that point) and shall not gain admission into it without punishment (for his sin). Surely he deserves punishment – due to the enormity of the sin – similar to those who perform the Major (Kabaa’ir) sins. Allaah may punish him in the Fire as long as He wishes, but none from amongst the people of Tawheed shall remain in the Fire eternally.
This is to be the way we understand all the Hadeeth that have a similar meaning. This understanding is to be used when seeking the meaning of his (sallAllaahu ‘alayhi wa sallam) statement: “The one who severs the ties of the womb shall not enter Jannah” or “You shall not enter Jannah until you believe. And you shall not believe until you love one another. Shall I inform you of something that if you do you shall (truly) love each other? Spread the greetings of Salaam amongst yourselves.”
This is the understanding that we are to have when pondering over the ahaadeeth that contain threats of Punishment. In this way we understand that the hadeeth is general and can be attributed to both the unbelievers and the Muslims.
If one was to say: “All the Muslims enter Jannah due to their Islaam.” The response is that not all Muslims enter Jannah without punishment. Surely the people who have been threatened (with punishment in the Hereafter due to their sins) shall enter into the Fire to remain in it for the period that Allaah so wills even though they are not unbelievers. The individual who has some Eemaan coinciding with major sins may enter into the Fire and exit from it as a result of the Shafaa‘ah (Intercession) of the Prophet or by other reported means as articulated by the Prophet when he (sallAllaahu ‘alayhi wa sallam) said:
“My Shafaa‘ah is for the people who commit Majors Sins from amongst my Ummah.” 
And he (sallAllaahu ‘alayhi wa sallam) said as is reported in the Saheeh: “I shall bring out of the Fire the one who possesses half a mustard seed of Eemaan.” 
In this way we understand what is in store for those whom Allaah has threatened with punishment – the murderer, fornicator/adulterer, the one who consumes intoxicants, and the one who misappropriates the wealth of the orphans, the one who witnesses falsehood and others who perform the deeds of the people of major sins. They – even if they are not unbelievers – are not deserving of the Jannah that they are promised (as Muslims) without first being (cleansed and purged through) punishment.
The madh-hab (way and belief) of Ahlus-Sunnah wal-Jamaa‘ah is that the Foosaaq (deviant sinners) from amongst the general body of Muslims are not going to be eternally punished in the Fire as held by the Khawaarij and the Mu‘tazilah. They are not complete in their religion (Deen), Eemaan and obedience to Allaah. They have good and bad deeds that necessitate a measure of punishment and reward. This is a concise dissertation regarding the issue.