First up, this is very much a debatable topic, and accordingly i adhere to USR becaus times are different, and if brother USR remembers we did have discussion about this earlier, because apostacy has different rulings with different time.
Secondly, here i will bring in few verses of the Quran and few hadith to back up the claim.
We have to understand Apostacy as a penalty is promised by Allaah in the Quran, than by the human.After that in again becomes situational based and then the word ‘renegade’ comes into picture.
My first Verse is,
There is no compulsion in religion Verse 2:256.
Now keeping the above verse in mind is apostacy a fair ruling then. One place in the Quran it states no compulsion in religion, and then if some disbelieves cut him down. But for a murtid who is the the one who punishes. For these verses in the Quran below clearly states if someone first believes and then disbelieves Allaah will penalise them.
Say, The truth is from your Lord: Let him who will believe, and let him who will, reject (it): for the wrong-doers We have prepared a Fire whose (smoke and flames), like the walls and roof of a tent, will hem them in: if they implore relief they will be granted water like melted brass, that will scald their faces, how dreadful the drink! How uncomfortable a couch to recline on!
[The Quran ; 18:29]
**90: Surely, those who disbelieve after their believing, then increase in unbelief, their repentance shall not be accepted, and these are they that go astray. **
91: Surely, those who disbelieve and die while they are unbelievers, the earth full of gold shall not be accepted from one of them, though he should offer to ransom himself with it, these it is who shall have a painful chastisement, and they shall have no helpers.
[The Quran ; 3:90-91]
Please also refer verses 4:137-138. Also check 18: 21,22.
So infact in the above verses the person is continually inclined towards disbelief even here there was no question of apostacy. Well, again the reason is its situational based and if charged for treason.
So we find no evidence from the Quran. One more interesting stuff to note here is just suppose a person disbelieves in Islam, but still just to show to the outside world is still a Muslim but this is an act of hypocrisy, and believe me hypocrisy is a much bigger sin compared to Apostacy.
Now let me back it up with hadith also,
Narrated by Bukhari Vol 9, hadith 316
Jabir ibn `Abdullah narrated that a Bedouin pledged allegiance to the Apostle of Allah for Islam (i.e. accepted Islam) and then the Bedouin got fever whereupon he said to the Prophet (peace and blessings be upon him) “cancel my pledge.” But the Prophet (peace and blessings be upon him) refused. He (the Bedouin) came to him (again) saying, “Cancel my pledge.” But the Prophet (peace and blessings be upon him) refused. Then he (the Bedouin) left (Medina). Allah’s Apostle said, “Madinah is like a pair of bellows (furnace): it expels its impurities and brightens and clear its good.”
This has always been my say someones wants to quit Islam then let him do it.