Nutshelled; Kill apostates unless you are allied with them or they offer a treaty and are not attacking you.
Qur`an 4:88-91
The four verses, 4:88-91, when carefully examined, also show that the Qur`anic perspective conflicts with the death penalty for apostasy. The first two verses state:
Then what is the matter with you that you are divided into two groups regarding the hypocrites? God has cast them backward (arkasa) because of what they have earned. Do you want to guide him whom God has made to go astray? And he whom God has made to go astray, you will not find for him any way. They wish that you reject faith as they have done, so that you all become the same. So take not protectors/friends from them till they emigrate in the way of God. But if they turn away, seize them and kill them wherever you find them, and take neither protectors/friends from them nor helpers. (4:88-89)
This passage begins by talking about hypocrites, that is, people who had declared themselves Muslims but in their hearts had decided not to believe in the teachings of Islam. The demand that they should do hijrah fi sabil allah (emigrate for the sake of God) shows that they are not the hypocrites of Madinah but are living among non-Muslims in Makkah and possibly elsewhere. Verse 98 of the same surah shows that these people were not doing hijrah despite the fact that they were able to. The reason for their not doing hijrah was their hypocrisy. Makkan non-believers who had persecuted Muslims for years, would not have tolerated in their midst any true Muslims. They would have accepted among them only those “Muslims” who had stopped taking their “islam” seriously and felt more comfortable among non-believers, hostile to Islam, than among Muslims. These hypocrites pretended to be Muslims because they wanted to be secure from both sides (see 4:91). And Makkan non-believers did not force them to publicly renounce their “islam” because they found them useful for gathering information about Muslims or for some other subversive actions against the ummah.
In order to defeat these hypocrites in their game and force them to clearly choose between Islam and kufr, God commanded them to do hijrah. Their obedience to this command meant that they had chosen Islam and their disobedience meant that they had chosen kufr. Those who chose kufr in this way became apostates, since previously they called themselves Muslims. Thus the verses are a source of guidance for us regarding the way the apostates are to be treated.
At first sight the words “seize them and kill them wherever you find them” would suggest that they are to be killed. But this is quickly seen to be wrong if we read the next two verses:
Except those who join a group between you and whom there is a (peace-) treaty or those who approach you with their hearts restraining them from fighting you or fighting their own people. Had God willed he would have given them power over you and they would have fought you. So if they withdraw from you and do not fight you but give you (guarantees of) peace, then God has opened no way for you against them.
You will find others that wish to gain your confidence as well as that of their people. Every time they are sent back to temptation they give in to it. If they do not withdraw from you nor give you (guarantees) of peace, nor restrain their hands, seize them and kill them, wherever you find them. In their case We have provided you with a clear warrant against them. (4:90-91).
These verses clarify the command “seize them and kill them”. The apostates who rejected Islam by failing to emigrate as commanded by God are divided into three categories:
1)Those who ally themselves with a group with whom Muslims have a peace treaty;
2)Those who want to keep neutrality, committing themselves to peace with both the Muslims and their own people who had not accepted Islam;
3)Those who provide no real guarantee of peace to Muslims and by all indications ally themselves with non-believers engaged in hostilities towards Islam.
The first two types of apostates are to be left in peace while the third one is to be treated like any non-believers in a state of war: they are to be seized and killed wherever they are found. Notice that the Qur`an uses the words “God has opened no way for you against them” in connection with the apostates of the first two types. This means that the Qur`an actually prohibits killing those apostates who want to live in peaceful terms with the Muslims.
Thus according to the Qur`an the apostates are to be treated like other kuffar: If they want to live in peace with the Muslims, they are to be left in peace and if they assume a hostile attitude, then they are to be treated accordingly.