Assalamu alaikum wr wb
Bismillahir Rahmaanir raheem
In the name of Allah, most Compassionate, most Merciful
The term in Arabic for convert is Aslam. When Muslim scholars speak about conversion they say wal kafir idha aslama. In the Qur'an the term "repentance" (Tawbah) is also used: "...But if they (the pagans, polytheists) repent, and establish regular prayers and practice regular charity, then open the way for them..." (9:5). There are several steps to be discussed regarding the process:
How To Become A Muslim. For the common unbeliever to become a Muslim, he must pronounce the two statements of the Shahadah: "I bear witness that there is no god but Allah, and I bear witness that Muhammad is His servant and Messenger." A person who has previously believed in Judaism or Christianity has to add: "And I bear witness that Jesus is the servant of Allah, His Messenger, and His word which He gave to Mary, and a spirit from Him." This expression is to signify a rejection of both the Jewish misconception and derogation of Jesus, and the Christian misconception and exaggeration of his position. The Prophet (s.A.w.) said: "Whoever testified that there is no god but Allah, alone, without partners with him, and that Muhammad is His servant and Messenger, and His word which He has thrown into Mary, and a spirit from Him, and that Paradise is true and that Hell is true - Allah will let him enter Paradise with what action he did." (Bukhari, Muslim)
Witnesses To Conversion From a religious point of view, there is no need for any witnesses to a conversion, but for a person from a non-Muslim background to be known as a Muslim, he or she must officially register their acceptance of Islam so as to be treated as a Muslim in all aspects of life, such as civic and personal matters. This is especially important in non-Muslim countries: I am aware of the case of an elderly, hospitalised brother who embraced Islam sometime before passing away. Nearly all his visitors during this period were Muslims, but because his conversion was not recorded officially, his body was handed over to his immediate family who carried out the funeral procedures according to non-Islamic ways.
Ghusl Once the Shahadah has been pronounced the new convert becomes subject to the rules of Islam. If the new Muslim is an adult, male or female, Ghusl is obligatory to enable the person to perform his or her prayers. It is not permitted, when a person comes to announce his conversion, to ask him or her to go and perform Ghusl first; this means delaying his conversion, and no-one knows what may happen during this delay. Abu Hanifah (r.a.) says that there is no obligation on the convert to perform Ghusl because Allah (s.w.t.) says: "Say to the unbelievers, if (now) they desist (from unbelief), their past would be forgiven them..."(8:38). Many people embraced Islam and the Prophet (s.A.w.) did not ask them to take a bath. When Amr Ibn al-'As accepted Islam, the Messenger of Allah said to him: "Did you not know that Islam wipes away what happened before, and repentance wipes out what was before." The explanation to this apparent contradiction is that Allah will forgive sins according to a person's rights. The obligation to perform Ghusl comes after conversion, to enable the new convert to offer his or her prayers. When Qays Ibn Asim accepted Islam, the Prophet (s.A.w.) asked him to take a bath.
Circumcision The male convert should be circumcised, as this is part of the natural manners recommended in Islam. If circumcision would pose any risk to health it may be delayed until the person is fitter and more able to cope with it. The scholars refer to the example of Prophet Ibrahim (a.s.) who circumcised himself at the age of eighty. Some Muslim scholars would not accept an uncircumcised person leading prayers. Incidentally, there is no requirement of circumcision for females in Islam.
Shaving The Head, Removing Bodily Hair It is recommended for the new convert to shave his head (men only) and to remove body hair from the armpits and the private parts (both sexes). It is reported that Kulayb came to the Prophet to declare his Islam, and to one he told him to shave his hair, and to another convert he said: "Clean off the hair which grew while you were a disbeliever, and circumcise yourself."
Changing The Name If the name is an ordinary one according to the culture of the person accepting Islam, there is no need to change it. But if it has a meaning which is objectionable on Islamic grounds (such as Abd al-Masih, the servant of the Messiah), it has to be changed.
Family Matters If the convert is in a marriage which is not acceptable in Islamic law, it is automatically nullified when he accepts Islam. For example marriage to a blood relative who is actually prohibited for marriage (Mahram) is of course null and void. If a man was married to two sisters, on accepting Islam he would have to choose between them. If a Muslim convert's wife remains a Jew or Christian, the marriage remains valid, but if she is of any other religion, the marriage is nullified. Underage children become Muslim once one of the parents accepts Islam. Adult children are free to choose.
Wills And Inheritance A difference of religion prevents inheritance; a Muslim cannot inherit from a non-Muslim or vice versa. Inheritance here refers to cases where a person dies in the state (without having made a will) and the estate is distributed to heirs according to the law of the land. According to Islamic law, a Muslim cannot inherit from a non-Muslim relative in this manner. Wills, on the other hand, do make a difference: a Muslim may accept what has been left to him in a will by a non-Muslim relative. A Muslim with non-Muslim relatives may leave up to one-third of his estate to them in his will, but the other two-thirds must go to Muslim relatives.