[gdhbcc]

Depends on the place I suppose. In Portugal it was primarily because of religion (many time out of fear that they had secretly kept their Jewish religion, rather than actually converting to christianity).

It doesn't really make sense to talk about the expulsions in the 1500s as being motivated by race, given that there was no meaningful difference in race between the Jewish and Christian populations in the area, and they had widely intermingled.

While I have read plenty of accounts of riots and expulsions that either explicitly or implicitly state their reasons as being motivated by fears of new Christians still Secretly practicing Judaism, I haven't seen a single account naming race or some ethnic distinction as the cause.