Should you continue to live your life as false Muslim or you should confront your family and friends and confess your situation?
What does Quran say about that situation? What are the proscribed punishments if any?
Hi kolja, I'll try to answer your question with surah Al-Munafiqun (The Hypocrites) below,
When the hypocrites come to you, [O Muhammad], they say, "We testify that you are the Messenger of Allah ." And Allah knows that you are His Messenger, and Allah testifies that the hypocrites are liars. (QS. Al-Munafiqun: 1)They have taken their oaths as a cover, so they averted [people] from the way of Allah. Indeed, it was evil that they were doing. (QS. Al-Munafiqun: 2)That is because they believed, and then they disbelieved; so their hearts were sealed over, and they do not understand. (QS. Al-Munafiqun: 3)
the verses say that someone in your question which you declared as
Muslims stop being believers are called
As your main question is
Should I continue to live my life as false Muslim or I should confront my family and friends and confess my situation
I'd like to called it as The Hypocrite rather than
people of other religions or atheists
Another part of your question about
What does Quran say about that situation?
What are the proscribed punishments if any?
I will answer it based on surah Al-Munafiqun verse 5 and 6
And when it is said to them, "Come, the Messenger of Allah will ask forgiveness for you," they turn their heads aside and you see them evading while they are arrogant. (QS. Al-Munafiqun: 5)
The situation is have been happened in Rasulullah era, they are arrogant, the one who called The Hypocrite in this case is Abdullah bin Ubay bin Salul (that was I learnt in my childhood). But this condition can applied to other people.
It is all the same for them whether you ask forgiveness for them or do not ask forgiveness for them; never will Allah forgive them. Indeed, Allah does not guide the defiantly disobedient people. (QS. Al-Munafiqun: 6)
based on verse 6, it's hopeless to you if you ask forgiveness for them since as you say, maybe they will
confront his family and friends and confess his situation.
Why he will do that?? because The Hypocrites are arrogant.
[Al-Hujurat 14] The bedouins say, "We believe." Say [to them], "You have not believed; rather say 'We have submitted [in Islam],' for faith has not yet entered your hearts. And if you obey Allah and His Messenger, He will not deprive you from your deeds of anything. Indeed, Allah is Forgiving and Merciful."
Islam is, fundamentally, submission to God's laws and His authority. In the hadith of Jibril, a clear distinction is made between "Islam" and "Iman"; whereas Iman is about belief in God and the unseen and all that entails, Islam is only defined in relation to its outward actions (e.g. fasting, salat, zakat).
The hypocrites are those who claim to be Muslims while rejecting God's authority, those who (for example) only perform the duties of Islam when they are seen by others, but abandon them — or even work against Islam — when they are alone. The apostates, on the other hand, are those who once claimed to be Muslim, but no longer follow, nor claim to follow, God's law at all.
However, just because one lacks iman does not necessarily make one a "false Muslim." One can be weak in faith — so weak as to be practically non-existant — without actually rejecting God's authority; as long as he continues to obey God's commandments, in private as well as in public, he is still Muslim (at least so far as worldly punishments are concerned).
If a person stops believing in Islam then he is free to follow it as a culture or as if he is the citizen of the "nation" of Islam without following its laws. Many citizens of a country don't believe in the laws of that country and are anti govt that does not stop them from being the citizen of the country. It is foolish for the citizen of a country to go around and publicize that he does not want citizenship and speak ill of the nation, this would only invite trouble and harassment to the person. Moreover if one person thinks like that then the there are 1000+ others who love their nation and would like the one who has disbelieved to remain in the fold of Islam , in hope that in the future even if he does not believe , his progeny would believe as they are more closer to Islam than people of other religion\ Atheists. So yes a person who does not believe in Allah (Atheist) can remain to be a part of Islam. It is the most practical thing for such people to remain in the fold of Islam and probably your friend has also realized this.
I assume that your friend is young, it is very common in non Muslim countries to have atheist Muslim youths, a significant chunk of them are expected to transition as normal Islamic believers as and when they understand their religion, and this too is very common.
A person born is a muslim family is a muslim by birth. There comes a time (usually) when he accepts (or rejects) is willingly. This happens when he comes of age and has an inclination to think in this direction.
Allah has made this world on a rule that we will be tested in this world and the result will be announced in the next world. What good is a test if you get punishment at the first wrong doing, or rewarded at the first good deed. So you a free to choose whether you think that Islam is the right religion or not, or God exists or not.
Allah has not only given his introduction though prophets but first though inspiration to every single human being in his subconsciousness. If you remain true to yourself, you will eventually find that there is a God and you will meet him someday.
You can choose to proclaim it or keep it hidden. It does not matter to Allah, he knows it and he will judge you accordingly.