Is a Christian girl who publishes indecent pictures—in the view of some—considered unchaste, and is marriage to her invalid, taking into consideration the prevalence of this idea in the West?

It is permissible for a Muslim man to marry a chaste Kitabiyyah (Jewish or Christian woman), based on the verse: ﴿وَالْمُحْصَنَاتُ مِنَ الَّذِينَ أُوتُوا الْكِتَابَ مِنْ قَبْلِكُمْ﴾ (and the chaste women from among those who were given the Scripture before you). A chaste woman is one who is not known to commit fornication. As for non-Kitabiyyah women, such as idolaters and atheists, it is not permissible to marry them.

It should be known that marrying chaste Muslim women is preferable and further from temptation. As for the issue of a Kitabiyyah's unveiling (tabarruj), it does not invalidate her marriage, just like a Muslim woman's.

However, marrying a Kitabiyyah in non-Muslim lands is fraught with dangers, as she might gain control over the children and change their religion. Therefore, this marriage is disliked if chaste Muslim women are available. The jurists have stipulated its dislike, and Sheikh Ibn Baz warned against the danger of the children being Christianized or the husband being drawn to disbelief.

A man should choose a wife who possesses religion and good character, and reject those who are content with nothing but spreading pictures and nudity.