Mat 19:12 For there are some eunuchs, which were so born from [their] mother's womb: and there are some eunuchs, which were made eunuchs of men: and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven's sake. He that is able to receive [it], let him receive [it].

Christ offers only one alternative to marriage, abstaining from sex, however, the term here doesn't describe this as a a passive, inactive role. The word eunuch means literally a "bed watcher," which refers to the role of castrated men guarding sleeping women. (However, it is possible that Matthew didn't know any other word for castration, since the term he uses from making a eunuch is not based on the more direct terms for castration (anorchos, alithos)).

Christ says that people can abstain from sex either because they are born disinterested in sex, because they are castrated by others, or because they are able to control themselves but only by heaven's power ("by heaven" not "for heaven" as translated above. See below). Note that none of these is really by ones own power. In Christ's parsing of the universe into body, mind, relationships, and spirit, one form of abstainence from the body, another from relationships (society), and the final is from spirit. None of these paths are from the mind, that is, from our reason alone, and none of them from our own power. Even if choose abstinence, we need the help of heaven to make it possible.

What can we do of our own minds? We can "make room for another," which is translated as "receive." This idea and term (chôreô) was introduced in the previous verse, referring to our nature. (The term is the basis for "choreograph," that is, planning a dance.) Here the term used for "be able" means specifically to have it within our own power. The bottom line is that, yes, marriage is difficult, but we can "make room for another" out of our own capabilities. The alternative, that is, "bed watching," is only possible by powers outside of ourselves. As Christ started by saying, men and women were created to be together. This is our nature no matter how difficult it is to stay together. Making room for another is difficult and doesn't get any easier by changing parthers.

Alternative: For there are those without sexual desire who are born as eunuchs from their mother's womb, who are castrated by men, and who control themselves by heaven's power. Let those who are able to make room from others by their own power make room for others.

I have often wondered in reading this verse in English if Christ was referring here to gay people. I thought Christ might be saying that some people are born without an interest in the opposite sex. After all, how many people are born without sex organs entirely? Not many. However, if this does refer to gay people, the message is clear that those people should abstain from sex. It certainly isn't that they should marry people of the same sex, which goes against the message of the entire series of verses, which is about making room "for the other."

"Eunuchs" is from eunouchos, which means literally "bed watcher," that is, acting as a chamberlain, referring to the fact that castrated men were used as guards for woman's bedrooms. "Made eunuchs" is from a verb form of the word, eunouchizô, which is only used here in the NT.

"Born" is from gennaô, which mean "to produce,"to create," and, specifically of women, "to bring forth," and "to bear children."

"Of men" is from hupo anthropos, which means "by man" or "under man."

"For the kingdom of heaven's sake" is from dia basileia ouranos. Dia means "through" here, in the sense of "by means of." The sense is here is "by the power of heaven."

"Is able" is from dunamai which means "to have power by virtue of your own capabilities," "to be able," and "to be strong enough."

"Receive" is from chôreô, which mean "to make room for another," "withdraw," "retire," "advance," "go forward," "make progress," and "have room [for a thing]."