If a Christian girl converts to Islam and marries a Muslim boy for say a meher of Rs 1 lakh.
If her husband divorces her later, she gets to keep the meher.
My question is: after receiving the meher post-divorce, if that girl converts back to Christianity, will she still have the meher or will she have to return it back?
Note that in Islam scholars say that mahr is not a condition for marriage to be valid. Read for example in al-Mawsu'a al-Fiqhiyya الموسوعة الفقهية:
والمهر ليس شرطاً في عقد الزواج ولا ركنا عند جمهور الفقهاء، وإنما هو أثر من آثاره المترتبة عليه، فإذا تم العقد بدون ذكر مهر صح باتفاق الجمهور، قال الله تعالى: لاَّ جُنَاحَ عَلَيْكُمْ إِن طَلَّقْتُمُ النِّسَاء مَا لَمْ تَمَسُّوهُنُّ أَوْ تَفْرِضُواْ لَهُنَّ فَرِيضَةً ـ
فإباحة الطلاق قبل المسيس وقبل فرض صداق يدل على جواز عدم تسمية المهر في العقد
(My own translation take it with care)
Mahr is not a condition for the validity of a 'aqd of nikah nor is it a pillar in the view of the majority of scholars, but it is (a trace or) a result of its results of it, so if a 'aqd has been made without quoting a mahr it is valid as per the view of the majority, as Allah the Almighty says: "There is no blame upon you if you divorce women you have not touched nor specified for them an obligation.(2:236)
therefore the permission for talaq before consummation of the marriage and before obligating the mahr (or sadaaq) is an evidence that it is allowed not to name or quote a mahr at the 'aqd an-Nikah.
But even if the mahr is not a condition for the validity of a marriage it is a clear right of the wife, which nobody can reject or hinder her from once this marriage was consumated. And it is her right to ask for it and only she can refuse to take it or take parts of it based on:
And give the women [upon marriage] their [bridal] gifts graciously. But if they give up willingly to you anything of it, then take it in satisfaction and ease. (4:4)
Even if the verse (2:236) allows delaying mahr, one must know that once the marriage is consumed the mahr becomes an obligation on the husband no matter if his wife is a Muslim or from among people of the book (note that conversion from Islam to any other religion -without any exception- is considered as apostasy and if the wife doesn't turn back in the fold of Islam this marriage becomes invalid, see What evidence is there that a Muslim man can not marry a chaste woman of the book if she is an ex-Muslim?) as Allah says:
... . So for whatever you enjoy [of marriage] from them, give them their due compensation as an obligation. And there is no blame upon you for what you mutually agree to beyond the obligation. Indeed, Allah is ever Knowing and Wise. (4:24)
Ibn Kathir commented this saying:
(So with those among them whom you have enjoyed, give them their required due,) means, to enjoy them sexually, surrender to them their rightful dowry as compensation. In other Ayat, Allah said,
(And how could you take it (back) while you have gone in unto each other 4:21),
(And give to the women (whom you marry) their dowry with a good heart 4:4), and,
(And it is not lawful for you (men) to take back (from your wives) any of what (dowry) you gave them 2:229)
(Source qtafsir)
...
The meaning of these Ayat is: If you have stipulated a dowry for her, and she later forfeits it, either totally or partially, then this bears no harm on you or her in this case. Ibn Jarir said, "Al-Hadrami said that some men would designate a certain dowry, but then fall into financial difficulties. Therefore, Allah said that there is no harm on you, O people, concerning your mutual agreement after the requirement (has been determined).'' meaning, if she gives up part of the dowry, then you men are allowed to accept that.
(Source qtafsir)
So if the marriage was consummated and this toke place before the wife left Islam she has full right on the dowry. And this seems to be the situation described here as she has left Islam after divorce which leads to the assumption that the marriage has been consummated before this divorce.
"And give the women their dowries with a good heart..." [Noble Quran 4:4]
"...So for that pleasure which you have enjoyed from them, give them their prescribed compensation.. " [Noble Quran 4:24]
As you can see, the first part of the surah Allah (SWT), states to "Give the women their dowries with a good heart", meaning the said (Dowry Is already paid to the women In question).
"...All others have been made lawful for you provided you seek (them in marriage) with your property..." [Noble Quran 4:24]
Understand that "This Is a commandment from Allah (SWT)", when Allah (SWT) states "And give the women their dowries with a good heart...", this Isn't a request (It's not as If) Allah (SWT) stated "If you want to give them or not" but HE/Allah (SWT) stated "And give the women their dowries with a good heart".
That should be the end of the discussion (As for what, that women does afterwards shouldn't be your concern) as you already (Divorced her). Yet lets continue (For the sake of the question).
"...So for that pleasure which you have enjoyed from them, give them their prescribed compensation.. " [Noble Quran 4:24]
The next Ayat Allah (SWT) states the reason as to why (You/The Husband) have to pay this "Dowry" and the reason being Is because of the "Pleasure which you have enjoyed from them" and for the said "Pleasure" Allah (SWT) states "Give them their prescribed compensation" In this case (Dowry) that Is theirs to keep.
SAHIH INTERNATIONAL
Divorce is twice. Then, either keep [her] in an acceptable manner or release [her] with good treatment. And it is not lawful for you to take anything of what you have given them unless both fear that they will not be able to keep [within] the limits of Allah . But if you fear that they will not keep [within] the limits of Allah, then there is no blame upon either of them concerning that by which she ransoms herself. These are the limits of Allah, so do not transgress them. And whoever transgresses the limits of Allah - it is those who are the wrongdoers. 2:229
Again, I'd say that's pretty cut and dry (But with limited understanding of such matters) I read the Quran for that which It Is. Also, why do you really wish to "Tempt the wrath and punishment of Allah (SWT) for monetary things? Money comes and goes (That's life) but you've given this (Dowry) to a women, whom, you were married to at one point correct? Than you went onto that women+That women did do the house-hold chores and cooked and cleaned and took care of your needs, be In (Mental/Physical/Emotional and ETC) and she was a companion to you (At one point), so why would you wish to "Harm her), even "If she changed Religions"? That Is a matter for "her and Allah (SWT)" not "You and her and Alllah (SWT)".
And Allah Knows best but that Is the my answer to the question (Hope this helped).
