[Q]: Some women give preference to the societal norms of Europe or the West in general; or in the un-Islamic lands, saying: “Plural marriage is unlawful.” While we have a legislative ruling permitting polygamy. What is the ruling on leveling this (type of) charge against Islām.

[A]: Whoever hates plural marriage or claims that not having plural marriage is better, then he is a kāfir and an apostate from Islām. This is because he, and we seek refuge with Allāh, is a rejecter of the ruling of Allāh and hates that which Allāh has legislated. Allāh, Glorified be He, says:

ذَلِكَ بِأَنَّهُمْ كَرِهُوا مَا أَنْزَلَ اللَّهُ فَأَحْبَطَ أَعْمَالَهُمْ
“That is because they hate that which Allāh has sent down (this Qurʾān and Islamic laws, etc.), so He has made their deeds fruitless.”
[Sūrah Muḥammad, 47:9]

Whoever dislikes that which Allāh has sent down then his deeds are fruitless. So whoever dislikes plural marriage or holds that the sharīʿah has been oppressive; or that the ruling of Allāh regarding this is deficient or not good; or that that which they do within the lands of the Christians from monogamous marriage is better and more befitting, then all of this constitutes apostasy from Islām, and we seek refuge with Allāh; just as the one who says that the obligation of Ṣalāt is not appropriate. (Saying for example): “If the people where to be left without (having to offer) Ṣalāt, this would be better; or without having to fast, this would be better; or without having to pay Zakāt, this would be better.” Whoever says this, then he is a Kāfir. Likewise, whoever says that not praying is more befitting; or not fasting is more befitting; or not paying Zakāt is more befitting; or not making Ḥajj is more proper; (whoever says this) then he is a Kāfir. Likewise, if one were to say: “There is nothing wrong with ruling by other than the Sharīʿah; it is permissible.” Even if he says that ruling by the Sharīʿah is better, but he says that ruling by other than that which Allāh has sent down is permissible or it is good, all of this constitutes apostasy from Islām, and we seek refuge with Allāh.

The gist of the matter is, that whoever dislikes that which Allāh has sent down and that which Allāh has legislated then he is an apostate. Likewise, whoever loves or is pleased with that which Allāh has prohibited and says that it is good and that it is appropriate; such as fornication and stealing, then he is a Kāfir as well; and we ask Allāh for safety.

Translated by Raha ibn Donald Batts
Source:  http://www.sahab.net/forums/index.php?showtopic=90167