I abhor the concept of killing a person for leaving a religion. the Qur'an is quite clear there is to be no compulsion in religion. A person needs to be responsible only to God(swt) over their choice of religion. It is their own decision and they alone accept the result of the decision on judgement day.
Having been a Christian and now a Muslim, on a world wide basis, I do not see a person who leaves Islam as being in any more danger than a Christian who leaves Christianity. While typically "Christian Honor" killing are not called such I have found they do occur. Often called "Domestic Violence" with no further explanation. But I have found that it is not uncommon for a person who leaves Christianity in Italy, Spain, Greece and Portugal to become a victim of "Domestic Violence"
I know more than a few American Christians that have reverted to Islam and are afraid to have any family members know. It is one of the most common concerns I hear from recent converts to Islam.
Speaking as I Muslim.
I do not know who is a Muslim. No one does. That is only known to the person and Allaah(swt). None of us can see into another person's heart and thoughts. To be a Muslim it means a person is submitting to God(swt) to the best of their ability. If a person is Submitting to God(swt) they are Muslim even if they do not yet know they are Muslim.
Any one can claim to be a Muslim and not be one. Likewise there are probably people who claim not to be Muslim and are Muslims.
We do not know who is or who isn't a Muslim, we only know who claims to be.Muslim
I think the same goes for all religions. We do not know, we only know what a person claims to be.
Just my opinion I do not believe a person is any religion if they are not willing to say they are that religion, no matter what the consequences.
In other words:
A Christian is not a Christian If they are not willing to say they are Christian, no matter what the consequences.
A Jew is not a Jew If they are not willing to say they are Jewish, no matter what the consequences.
A Muslim is not a Muslim If they are not willing to say they are Muslim, no matter what the consequences.
etc
I think some Missionaries play the threat of death card to show the need of more Evangelizing. and to be able to claim higher converts than they actually have.
I was once a Missionary "converting" Muslims. In my ego I thought I had won more souls than the numbers showed, because I believed most converts were afraid to say they were Christian.
That verse is about forcing a person into Islam, not about one leaving Islam.
002.256 Let there be no compulsion in religion: Truth stands out clear from Error: whoever rejects evil and believes in Allah hath grasped the most trustworthy hand-hold, that never breaks. And Allah heareth and knoweth all things.
002.257 Allah is the Protector of those who have faith: from the depths of darkness He will lead them forth into light. Of those who reject faith the patrons are the evil ones: from light they will lead them forth into the depths of darkness. They will be companions of the fire, to dwell therein (For ever).
This is the verse used by Islamists for the ok to kill apostates, those once Muslim now hypocrites:
004.088 Why should ye be divided into two parties about the Hypocrites? Allah hath upset them for their (evil) deeds. Would ye guide those whom Allah hath thrown out of the Way? For those whom Allah hath thrown out of the Way, never shalt thou find the Way.
004.089 They but wish that ye should reject Faith, as they do, and thus be on the same footing (as they): But take not friends from their ranks until they flee in the way of Allah (From what is forbidden). But if they turn renegades, seize them and slay them wherever ye find them; and (in any case) take no friends or helpers from their ranks;-
Then for those who follow hadith also-
Bukhari, Volume 8, Book 76, Number 586: Narrated Ibn Al-Musaiyab: The companions of the Prophet said, "Some men from my companions will come to my Lake-Fount and they will be driven away from it, and I will say, 'O Lord, my companions!' It will be said, 'You have no knowledge of what they innovated after you left: they turned apostate as renegades (reverted from Islam).
Bukhari, Volume 8, Book 76, Number 587: Narrated Abu Huraira: The Prophet said, "While I was sleeping, a group (of my followers were brought close to me), and when I recognized them, a man (an angel) came out from amongst (us) me and them, he said (to them), 'Come along.' I asked, 'Where?' He said, 'To the (Hell) Fire, by Allah' I asked, 'what is wrong with them' He said, 'They turned apostate as renegades after you left.' Then behold! (Another) group (of my followers) were brought close to me, and when I recognized them, a man (an angel) came out from (me and them) he said (to them); Come along.' I asked, "Where?' He said, 'To the (Hell) Fire, by Allah.' I asked, What is wrong with them?' He said, 'They turned apostate as renegades after you left. So I did not see anyone of them escaping except a few who were like camels without a shepherd."
Bukhari, Volume 9, Book 83, Number 17: Narrated 'Abdullah: Allah's Apostle said, "The blood of a Muslim who confesses that none has the right to be worshipped but Allah and that I am His Apostle, cannot be shed except in three cases: In Qisas for murder, a married person who commits illegal sexual intercourse and the one who reverts from Islam (apostate) and leaves the Muslims."
Bukhari, Volume 9, Book 84, Number 57: Narrated 'Ikrima: Some Zanadiqa (atheists) were brought to 'Ali and he burnt them. The news of this event, reached Ibn 'Abbas who said, "If I had been in his place, I would not have burnt them, as Allah's Apostle forbade it, saying, 'Do not punish anybody with Allah's punishment (fire).' I would have killed them according to the statement of Allah's Apostle, 'Whoever changed his Islamic religion, then kill him.'
Bukhari, Volume 9, Book 84, Number 58: Narrated Abu Burda: Abu Musa said, "I came to the Prophet along with two men (from the tribe) of Ash'ariyin, one on my right and the other on my left, while Allah's Apostle was brushing his teeth (with a Siwak), and both men asked him for some employment. The Prophet said, 'O Abu Musa (O 'Abdullah bin Qais!).' I said, 'By Him Who sent you with the Truth, these two men did not tell me what was in their hearts and I did not feel (realize) that they were seeking employment.' As if I were looking now at his Siwak being drawn to a corner under his lips, and he said, 'We never (or, we do not) appoint for our affairs anyone who seeks to be employed. But O Abu Musa! (or 'Abdullah bin Qais!) Go to Yemen.'" The Prophet then sent Mu'adh bin Jabal after him and when Mu'adh reached him, he spread out a cushion for him and requested him to get down (and sit on the cushion). Behold: There was a fettered man beside Abu Muisa. Mu'adh asked, "Who is this (man)?" Abu Muisa said, "He was a Jew and became a Muslim and then reverted back to Judaism." Then Abu Muisa requested Mu'adh to sit down but Mu'adh said, "I will not sit down till he has been killed. This is the judgment of Allah and His Apostle (for such cases) and repeated it thrice. Then Abu Musa ordered that the man be killed, and he was killed. Abu Musa added, "Then we discussed the night prayers and one of us said, 'I pray and sleep, and I hope that Allah will reward me for my sleep as well as for my prayers.'"
Bukhari, Volume 9, Book 84, Number 59: Narrated Abu Huraira: When the Prophet died and Abu Bakr became his successor and some of the Arabs reverted to disbelief, 'Umar said, "O Abu Bakr! How can you fight these people although Allah's Apostle said, 'I have been ordered to fight the people till they say: 'None has the right to be worshipped but Allah, 'and whoever said, 'None has the right to be worshipped but Allah', Allah will save his property and his life from me, unless (he does something for which he receives legal punishment) justly, and his account will be with Allah?' "Abu Bakr said, "By Allah! I will fight whoever differentiates between prayers and Zakat as Zakat is the right to be taken from property (according to Allah's Orders). By Allah! If they refused to pay me even a kid they used to pay to Allah's Apostle, I would fight with them for withholding it." 'Umar said, "By Allah: It was nothing, but I noticed that Allah opened Abu Bakr's chest towards the decision to fight, therefore I realized that his decision was right."