The Quran

يا أَيُّهَا الَّذينَ آمَنوا لا يَسخَر قَومٌ مِن قَومٍ عَسىٰ أَن يَكونوا خَيرًا مِنهُم وَلا نِساءٌ مِن نِساءٍ عَسىٰ أَن يَكُنَّ خَيرًا مِنهُنَّ ۖ وَلا تَلمِزوا أَنفُسَكُم وَلا تَنابَزوا بِالأَلقابِ ۖ بِئسَ الِاسمُ الفُسوقُ بَعدَ الإيمانِ ۚ وَمَن لَم يَتُب فَأُولٰئِكَ هُمُ الظّالِمونَ

Muhammad Asad

O YOU who have attained to faith! No men shall deride [other] men: it may well be that those [whom they deride] are better than themselves; and no women [shall deride other] women: it may well be that those [whom they deride] are better than themselves.¹ And neither shall you defame one another, nor insult one another by [opprobrious] epithets: evil is all imputation of iniquity after [one has attained to] faith;² and they who [become guilty thereof and] do not repent - it is they, they who are evildoers!

The implication is that believers, whether men or women, shall never deride one another (Zamakhshari, Baydawi).
This applies no less to the faith of the one who insults than to that of the insulted (Razi): cf. 6:82 - "[those who have not obscured their faith by wrongdoing".