>>37833141. What kind of interpretation of Islam does he follow?
2. Is your sister a christian virgin intending to marry him? (or a whore)
marriage in fundamentalist Islam isn't much more restrictive from the male perspective than loosely dating a women and having sex ...
... being able to tell her to fuck off three times to get rid of her unless she's pregnant.
Women are usually able to divorce if the man is impotent or broke.
If she is not a christian wishing to have a traditional marriage (in good and bad times)
with a life-long partner this doesn't really matter.
The guy converting her to Islam doesn't really make sense if she's a christian, it will not make a difference on his side
and only give her the right to divorce him and remarry if he goes broke.
Quran about marriage:
https://quran.com/4 