"Christians did them. That's my only point on the subject. I'm not making a judgment on whether the practice had Biblical support...only pointing out that such practices are not so alien, after all."
And that is a fair point, and quite correct.
I am just cautious to make the distinction between what Christians DO and what they are commanded to do.
In particular, I am sensitive to the tendancy of people to make equivolent how the Roman Catholic Church forced Christianity at the point of the spear/rifle with how Islam does the same today.
The distiction to be made, of course, is that what the RCC did was directly contrary to Christian scripture (with its emphasis on free acceptance) vs. forced conversion being a direct mandate of the texts of Islam.
I have no illusions of how far Christians fall from their mandate.
OK. From my perspective, however, the Roman Catholic Church was, and is, the largest denomination of Christianity. As a non-Christian, I really don't make much of doctrinal differences among the many, many denominations of Christianity.
Mortification of the flesh is uncommon today in the RCC, although it is not unknown among some monastic orders. Is it non-Biblical? I think a case could be made on both sides, but it's certainly not a major tenet of any denomination of Christianity, and is discouraged by today's RCC.
I do not decide whether someone is a "true" Christian. For me, it is enough that they say they are a Christian, just as it is enough for a Hindu to claim Hinduism. I leave the fine distinctions to the various denominations to argue over.