Is it permissible to declare someone an infidel (kafir) according to the prophetic hadith which states that one should not declare an infidel anyone who says "Lā ilāha illā Allah" (there is no god but Allah), taking into account that the Prophet did not fight the hypocrites, or do the Wars of Apostasy (Ridda) waged by Abu Bakr Al-Siddiq against those who withheld zakat, as well as the fact that sorcerers are considered infidels despite their prayers and fasting, indicate the permissibility of declaring someone an infidel?

It is not permissible to declare a Muslim an infidel unless they commit an act of disbelief (kufr) through belief, speech, or action.

Whoever commits any of these things leaves Islam, and the declaration of Tawhid "La ilaha illa Allah" (There is no god but Allah) will not benefit them, because they have committed an act that nullifies it. Among its nullifiers is refraining from obligatory duties, such as Zakat. Abu Bakr Al-Siddiq (may Allah be pleased with him) fought those who withheld Zakat, considering them apostates. The Companions and the Imams after them agreed on fighting them, even if they prayed and fasted.

Learning and practicing magic is an act of disbelief (kufr), and "La ilaha illa Allah" will not benefit its practitioner.

As for the Hadith of Usama (may Allah be pleased with him), it does not indicate that one who commits an act of disbelief is not an infidel. Rather, it indicates that it is not permissible to immediately kill someone who declares the two testimonies of faith. Then, their matter is examined: if they fulfill the requirements of the two testimonies and avoid their nullifiers, they are a Muslim; otherwise, they have apostatized.

It should be noted that declaring a specific individual an infidel is not permissible unless all conditions are met and all impediments are absent.