Why are blacks who convert to Islam so intolerable?

You always see blacks come out of prison converted to Islam and ranting on about how the Bible is made up, the Bible is full of lies, Muhammad this, Muhammad that. It's like they have verbal diarrhea and never stop bashing Christianity, despite most of the time being raised in a strict Christian family background.

I have seen black converts having violent arguments with Christian family members about the Church and trying to convert them.

When a black man converts to Islam, it's not done privately and quietly. They never stop going on about it and attacking Christianity at the same time.

Same with the women. Black women who convert nearly always wear the full black burka and immediately change their name to fatima khadijah al alluah or something like that and marry a Somalian or East African black Muslim.

What is it about Islam that gets them so riled up and excited?