The ruling about making takfîr upon a Muslim is dependant upon two conditions:-
Firstly: That the proof has been established that this is a matter which is from disbelief (i.e. which can cause a person to become a disbeliever).
Secondly: Then applying this ruling to one who does such an act, having knowledge that this action is an act of kufr (disbelief) and intending it. However, as for the person who is ignorant, then he does not become a kâfir (disbeliever) by such an act - due to the saying of Allâh - the Most High: “Whosoever opposes the Messenger, even after guidance has been plainly conveyed to him, and follows a path other than that of the Believers, We shall leave him in the path he has chosen and land him in Hell; what an evil destination.” [an-Nisaa 4:115] As His saying: “And AIlâh will never misguide a people after He has guided them, until He makes clear to them as to what they should avoid.” [at-Tawbah 9:115] And His saying: “And We never send punishment until We have sent a Messenger (to give warning).” [al-Israa 17:15]
However, if such a person is one who has transgressed by intentionally turning away from learning and seeking clarification, then he is not excused - such as the one who comes to know that such and such an action is an act of kufr, but he does not try to confirm it, nor does he attempt to seek further clarification - then such a person will not be excused in this case.
If, however, the person did not intentionally intend to commit kufr by such an action, then he will not be judged as a kâfir (disbeliever) on the basis of that action. For example: Being compelled to commit kufr, whilst the heart is at peace with îmân (faith). Or the example of one who looses control over his thoughts and does not know what he is saying - due to extreme joy, or other similar reasons. Such as the saying of the owner of the camel, so he lay under a tree waiting for death; and then suddenly the camels reigns are caught by the tree, so he takes hold of them and says: “O Allâh! You are my Slave and I am Your Lord,” committing a grave mistake due to his extreme joy. However, as for the one who commits an act of disbelief in jest, then he becomes a disbeliever, due to him intending disbelief - as the people of Knowledge have duly stipulated.