Answer
Salam (Peace) Adriana,
May Allah guide you, bless you, and reward you for your choice of Islam!
Please find part one of the answer to your question below. Find the second and final part at the link here.
Let me respond to your questions one by one.
First, I will answer your question about a Muslim leaving Islam.
Actually, there is a lot of confusion about this issue of apostasy. As you have noted, the Noble Quran does not prescribe death penalty for deserters of Islam, but rather states that they would be in Hell in the hereafter (2:217).
Here is a verse that directly refers to people who abandon their faith after accepting it:
{But those who reject faith after they accepted it, and then go on adding to their defiance of faith never will their repentance be accepted; for they are those who have [of set purpose] gone astray.} (Quran 3:90)
As you can see, there is no mention here of the death penalty for the deserters.
But there are Muslim scholars who believe in the death penalty for apostates because of hadiths (traditions of the Prophet) that mention it.
If we study the context of these hadiths, we can see that the ruling was with reference to certain specific cases of miscreants who wished to undermine Islam, by joining Islam first and then deserting it. This is mentioned in the following verse:
{A section of the People of the Book [Jews and Christians] say: “Believe in the morning what is revealed to the believers [Muslims], but reject it at the end of the day; perchance they may [themselves] turn back [from Islam].”} (Quran 3:72)
In order to protect Islam from such malicious attempts to subvert it, at a time when it was at its weakest from constant attack, the Prophet ordered the death penalty for such people, who not only apostated, but also committed crimes against the state.
If it had been a general ruling applicable for all occasions, this would have been stated in the Quran because it is a life-and-death question that affects the very fabric of Islam most seriously. The Quran says:
{Again and again will those who disbelieve, wish that they had bowed [to God’s will] in Islam. Leave them alone to enjoy [the good things of this life] and to please themselves: let [false] hope amuse them: soon will knowledge [undeceive them].) (Quran 15:2-3)
This verse clearly indicates that the disbelievers should be left alone.
Moreover, the killing of apostates would undermine the freedom of will Allah has bestowed on each human, as is made clear in the verses that say:
{If it had been thy Lord’s will, they would all have believed, all who are on earth! Will you then compel mankind, against their will, to believe! No soul can believe, except by the will of God, and He will place doubt (or obscurity) on those who will not understand.} (Quran 10:99-100)
{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 dwelling (resting place)!”} (Quran 18:29)
The verses quoted above are categorical that complete freedom of will is a condition for sincere and wholehearted submission to Allah Almighty, and no force should be used in this regard. This is because coercion does not go along with freedom of choice.
In addition, we may consider another verse that says:
{Those who believe, then reject faith, then believe [again] and [again] reject faith, and go on increasing in unbelief, — Allah will not forgive them nor guide them on the way.} (Quran 4:137)
The example of a person who vacillates between Islam and disbelief is cited here. Note the expression: {believe, then reject faith, then believe [again] and [again] reject faith}.
How can we imagine a person becoming a Muslim a second time, after rejecting faith once, IF he is to be killed after his rejection? The significance of this verse is one of free choice; though one is expected to be responsible in the use of that choice.
Thus we see that the general teaching of the Quran is one of freedom of choice and mercy.
Please continue reading part two at the link here.
Please continue feeding your curiosity, and find more info in the following links:
What does Islam Say About Freedom of Religion?
What Are The True Teachings of Islam?
A Revert: Shall I Marry A Married Man?
Can We Replace The Punishment of Zina?