Amongst the actions of kufr are those for which it is not necessary that a person make istihlaal of them (i.e. declare them to be lawful with his heart) before he be considered a disbeliever, outside the fold of Islaam.
Shaikh ul-Islaam Ibn Taymiyyah said, "And it is necessary for it to be known that the statement that 'the disbelief of the one who reviled (Allaah, the Messenger or the religion) is only disbelief because he made istihlaal of his act (i.e. declared this revilement to be lawful)' is a repugnant mistake and very great error...and this is from numerous angles..."
When a person reviles the Messenger (sallallaahu alaihi wasallam) or throws the Qur'an into some filth, or kicks the Qur'an without compulsion or out of error for example, then it is not a requirement that he makes or considers this act to be lawful (istihlaal) as a matter of belief before takfir is made upon him. Rather it is sufficient to known that he intended his act and did it wilfully, not being under compulsion or the likes.
As for Istihlaal (having the belief that something that Allaah has made unlawful is lawful), then it is of two types, that which is related to action, and that which is related to belief.
Shaikh Ibn Uthaimeen said, "Istihlaal is that a person believes that something that Allaah has made unlawful is lawful. As for Istihlaal of action, then we need to observe: If this Istihlaal (is related to something) that expels from the religion then a person becomes a disbeliever and apostate by it. So for example, if a person worked with usury (i.e. took or gave usury) without believing in its lawfulness, yet he persists in working with it, then such a one does not become a disbeliever because he did not declare it to be lawful. However, if he said, "Usury is lawful" and he intends by this the usury that Allaah has declared unlawful, then he becomes a disbeliever, since he is a denier (mukaddhib) of Allaah and His Messenger (sallallaahu alaihi wasallam). So in this circumstance, Istihlaal would be that of action and also that of belief, with his heart. However, the Istihlaal in action, we need to look at the action itself, is it something which in and of itself, expels from the religion or not? And it is known that consuming interest does not make a person a disbeliever, rather it is one of the major sins. However, if a person prostrated to an idol, then he becomes a disbeliever. Why? Because this act itself expels from the religion. This is the principle, however it is necessary for us to observe another condition, and this is that the person who made something lawful (by istihlaal) is not excused due to ignorance, for if he is excused due to ignorance, then he does not become a disbeliever."
So Istihlaal is of two types, that which is related to action and that which is related to belief. That which is related to belief is disbelief in all circumstances, regardless of whether this istihlaal was in relation to something that only reaches the level of minor kufr or something reaching the level of major kufr. For example, if one made fornication lawful as a matter of belief, or drinking and likes then he is a disbeliever. Likewise, if he made reviling the Messenger (sallallaahu alaihi wasallam) or the religion to be lawful, then regardless of whether he did the act or not, then he becomes a disbeliever by this istihlaal.
As for the istihlaal that is related to action, and this merely means that a person commits the act - in other words he makes it lawful for himself in terms of his action only, in the sense that he performs the act - then in such a situation one must look at the action he committed. Is it something that does not reach the level of major kufr? Such as fornication, stealing, gambling and the likes. In this case he is not a disbeliever by this Istihlaal of action. However, if it is an act (or statement) which expels from the religion, such as prostrating to an idol, then he becomes a disbeliever by this Istihlaal of action. And this is the principle concerning Istihlaal in the view of our Ulamaa. In light of this, the well known statement of Imaam at-Tahaawi, "We do not declare someone a disbeliever on account of a sin he committed, so long as he does not declare it lawful", is subject to the above clarification and is not taken absolutely.
With respect to Juhood, then Imaam Abu Ja'far at-Tahaawi said, "A servant does not exit from Imaan except by denial (juhood) of that which brought him into it." Shaikh Ibn Maani' commented, "He intends to refute the Khawarij and the Mu'tazilah by this, those who expel such a person from Imaan on account of a sin that he commited".
Shaikh Ibn Baaz said, further clarifying this, "This absolute generalisation requires further examination. For a disbeliever enters into Islaam by the two testifications if he had not uttered them previously, and if he was one who had uttered them, then he will enter into Islaam (again) after repenting from what had necessitated his disbelief. And a person can exit from Islaam without showing Juhood (denial, rejection) for many reasons which the people of knowledge have explained in the discussion of the rulings pertaining to the apostate. Amongst them: when he reviles Islaam or the Prophet (sallallaahu alaihi wasallam), or mocking Allaah, His Messenger or His Book or anything from His Legislation - free is he of imperfection - due to his saying, "Say: Was it in Allaah, His Signs and His Messenger that you were mocking? Do not seek to make excuses, for you have disbelieved after having had faith" (9:65-66). And also amongst such (actions) are worshipping idols, calling upon the dead, seeking help from them, seeking assistance from them and other such things. Therefore, whoever directs any of these (acts of worship) to other than Allaah, such as to idols, the angels, the jinn, those in the graves and others from the creation then such a one has committed Shirk with Allaah and has not actualised the meaning of "Laa ilaaha ilallaaha". All of these matters cause a person to exit from Islaam by unanimous agreement of the Muslims, and they are not from the matters of Juhood (denial, rejection). The proofs for these matters are well known from the Book and the Sunnah, and the Scholars have mentioned them in the chapters related to the ruling upon the apostate, so refer back to them if you will. And in Allaah lies success."
Just like our discussion with Istihlaal above, there are some actions for which Juhood, that is denial or rejection, is not a requirement for an action to be considered as major disbelief (kufr akbar) and what expels from Islaam. Rather such actions, in and of themselves are major disbelief and expel from Islaam. However, it is worth noting here, for the sake of completeness, that some of the Scholars have said that all of those matters which expel from Islaam, then the basis of all of that is Juhood (denial, rejection) of what the Messenger (sallallaahu alaihi wasallam) came with.
Shaikh 'Abdur-Rahmaan bin Naasir as-Sa'dee said, "Chapter: The Ruling upon the Apostate. "The apostate, murtad, is the one who exits from Islaam and enters into disbelief on account of an action, statement, a belief or doubt. And the Scholars - may Allaah have mercy upon them - have mentioned the specific detail and explanation of the matters by which a servant leaves Islaam. And all of them have their basis in the rejection, jahd, of what the Messenger (sallallaahu alaihi wasallam) came with, or rejection, jahd, of some of it. So the one who apostatises should be asked to repent during the course of three days. If he repents and returns, then fine, otherwise he is to be killed with the sword."
If one was to consider this statement to mean that the acts of kufr, such as those mentioned above in the statement of Imaam Ibn Baaz are not to be considered as major disbelief unless they are accompanied with Juhood, then this is an error. Rather such acts in and of themselves are major disbelief. Hence, there is an element of error in the statement above, if understood in this manner and it is not to be taken absolutely. However, if what is understood from it is that a person only becomes an apostate and the hadd punishment applied after the proof has been established (iqaamat ul-hujjah) and the person does not repent or desist or recant from his act or statement of kufr, but persists, then this is in conformity with the principle of takfir concerning those who fall into these acts which is establishment of the proof (iqaamat ul-hujjah). So if a person shows wilful denial (juhood) after this, he is then an apostate who is killed. Shaikh Muhammad bin Abdul-Wahhaab said, "[The apostate] is the one who has disbelieved according to the concensus (ijmaa) of the Muslims, and he is the one upon whom the proof has been established. The one upon whom the proof has not been established is not to be declared a disbeliever." 
In summary, we say that the amongst the actions of kufr are those which do not require that istihlaal of the heart or juhood of the heart be present for them to be considered actions of major kufr and which expel from Islaam.
 As-Saarim al-Maslool (p.514)
 Liqaa Baab al-Maftoo (no. 1200)
 Saihatu Nadheer (pp.48-49)
 Manhaj us-Saalikeen (p.112)
 As was pointed out by Shaikh Rabee' bin Haadee al-Madkhalee. Refer to Shaikh Alee Hasan's statement on the book "Ihkaam ut-Taqrir" in Al-Furqaan (no. 101)
 Aqidat us-Shaikh Muhammad bin Abdul-Wahhaab (p.208) of Shaikh Salih al-Ubood.