This is not a theology question; strictly interpretation/author intent.
"For there are eunuchs who were born that way, and there are eunuchs who have been made eunuchs by others—and there are those who choose to live like eunuchs for the sake of the kingdom of heaven. The one who can accept this should accept it."
I have always interpreted this verse as metaphorical (except for 'made eunuchs by others'). Does Koine scholarship have a consensus on whether the meaning is literal? In other words, does the verse approve of castration?
thank you for the question. There is no metaphor at all! Everything is meant to be literal and it has historically been recorded and confirmed, that there were several types of eunuchs.
I read the previous verses and I came to the conclusion that Matthew is against Moses' principles to abandon a wife out of iron-heartedness (probably from the mens' side) and wants to support the unification between husband-wife, explaining that this is the intended plan of God and that the couple has to stay together. The act where a man abandons his wife for a reason other than that, where the wife is a whore, is considered fornication. Then, he adds to this the verse that you sent me, as an example of a fact that some people are not even bound to (sexually) couple with women, because either nature or some bad luck - whatever - has rendered them incapable of this.
Castration was not encouraged by religion because it was considered a kind of rejection of God's gift to create children.
Generally, according to Zonaras' interpretations of earlier holy texts (12th century), those who castrated themselves or had themselves willingly castrated were considered "self-killers" and enemies of the God of Creation, as they could neither function as men, nor as women, i.e. couldn't create life; they were actually conspiring against their lives and had to be punished with a 3-year aphorism. Whereas, if they had themselves done so to heal their body from an illness, pain or other medical reason, it was totally accepted. In the event that they were castrated against their will (i.e. during a war, after torture etc.) they didn't suffer any punishment, too.
If you want to know more on how castration and eunuchs were treated in the Byzantine period, do not hesitate to ask, as I happen to have read much about this and can provide you with many details ;)
Have a good day.