It's being claimed by right wing sources that ISIS are teaching forced sex is not rape and bunred a woman for not engaging in an 'extreme sex act', ‘Forced sex ISN’T rape and they should be thankful’ – ISIS propaganda uses Koran to justify sex crimes,” “Islamic State burned a woman alive for not engaging in an ‘extreme’ sex act, U.N. official says,”
Let's be absolutely clear here, forced sex (rape) is not allowed in Islam. Here are the views of Muslim scholars on rape:
Reveal Muslim Scholars Views on Rape For All
And here is a piece on how rape of slaves is not allowed either:
Are Muslims Allowed to Rape Slave Women? No.
Having said that, I'm not sure if these reports of ISIS members claiming such things are true. What is clear is that Islam does not allow rape.
Lithuanian Woman on Islam
Russell Brand: Haters of Islam Encourage Muslims towards Extremism
Russell Brand - Muslims Treated Like Jews in Germany in the 30s
Did Muslims or Zionists Send Death Threats to Jenny Tonge?