Kafir in jurisprudential terminology
Kafir in a jurisprudential context mean: someone who does not believe in God, Prophet or one of the essentials of religion[1]. However, there are different viewpoints about instances of kafir[2]. In jurisprudence, kafir is differently divided depending on the subject matter it is studied in.
1-Ahlul Kitab [people of the Book]: They include Christians, Jews and Magianists –according to one opinion. Kafir in this category has some subcategories; they are either at war with Muslim community or not at war; those not at war also are divided into zemmi and non-zemmi.
1-1-Kafir as people of the Book at war with Muslim community is someone who opposes Islam and does not accept the conditions of zemmah (being under Muslims' protection).
1-2-Kafir zemmi as people of the Book is someone who has accepted conditions of zemmah and lives under Muslims' protection[3].
3-Murtadd is someone who has abandoned Islam after he accepted it[4].
4-Original kafir is an adult who was born of kafir parents and has chosen kufr [infidelity] by his free will.
5-Subordinate kafir is a kafir's child before puberty. He is considered as kafir and is called subordinate kafir.
Kafir in theological terminology
In theology, kafir is someone who has not accepted monotheism or divine unity or one of its necessary requisites, even if he utters shahadatayn [declaration of faith] and practices necessary religious rites. In other words, kafir in theology and kafir in jurisprudence are absolute generality and peculiarity; i.e. any kafir in its jurisprudential meaning is a kafir in its theological meaning, however, someone may be a kafir in its theological meaning but not a kafir in its jurisprudential meaning[5]. There is an overlapping relationship between the two.
Based on his belief in his kufr, a kafir in its theological meaning is divided into monotheistic and non-monotheistic kafir.
1-Non-monotheistic kafir: someone who does not believe in one of the essentials of monotheism. For example he does not believe in God's justice or he rejects the Resurrection or he does not accept one of the unambiguous doctrines of  the religion.
2-Monotheistic kafir: Based on his level of kufr, a monotheistic kafir is divided into kafir of unity of the divine essence[6], kafir of the unity of divine attributes[7], kafir of the unity of divine acts[8], este'ani kafir[9], kafir tashri'ei [legislative][10], kafir ebadi[11] and kafir hubbi[12].

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