Is Homosexuality a Sin?

EUNUCH DEFINED

Mathew 19:

4: And he answered and said unto them, Have ye not read, that he which made them at the beginning made them male and female,
5: And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh?

Here Jesus establishes the obligation for a man to marry and be faithful to one wife.

9: And I say unto you, Whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery: and whoso marrieth her which is put away doth commit adultery.

This reaffirms the requirement of monogamy.

10: His disciples say unto him, If the case of the man be so with his wife, it is not good to marry.

The disciples find this rule difficult to accept.

11: But he said unto them, All (men) cannot receive this saying, save they to whom it is given.

Jesus gives them an option. In this option he says that there are those that cannot accept this rule (to marry a woman and be monogamous). It is important to note here that he does not say “will not”, “would rather not”, “chose not to”, but he said “cannot”. This would imply that he was referring to people incapable (mentally, physically, or both) from living by the rules of men.

12A (first category): For there are some eunuchs, which were so born from their mother's womb:

I suspect this means all those incapable of consummating a relationship with a woman for whatever reason. (hermaphrodite or gay).

12B (second category): and there are some eunuchs, which were made eunuchs of men:

We pretty well all agree that these are actual eunuchs.

12C (third category): and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven's sake.

The church insists that these are simply celibate priests.
Logically neither of the first two groups would have any interest in women, so they would by their very nature be celibate.
The problem is that there is nothing said or done up to the moment that Christ said this that would indicate that celibacy was a requirement or even a virtue in priests. In fact, all indications are that it was disallowed. How do you “make yourself a Eunuch”? To be a eunuch 2000 years ago meant more than simple celibacy.
What Jesus said in Mathew 19 is completely self contained and can only be read literally. Well once again lets look at verse:

5: And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh?

No doubt about it, if you were capable of consummating a relationship with a woman, you were required to be married. More importantly, if you were a man you were required to be married. To declare yourself a eunuch was to declare yourself uninterested in women, a eunuch, a non man. This was understood readily 2000 years ago, but modern society has a hard time grasping it.
Having said this there were eunuchs that were allowed into the temple (natural eunuchs who were anatomically correct).
If Jesus was not married he was a eunuch by his own definition. He was anatomically correct because he regularly entered the temple. He had to be a natural eunuch (or married, one or the other).
Only by declaring themselves eunuchs were they exempt from the requirement of marriage. In fact, they were exempt from all rules pertaining only to “men”. The reason was that they were not considered to be “men”. Rules quoted about man being with man did not apply to eunuchs because eunuchs were not considered to be men. The sin was not being gay, but pretending to be men while engaging in gay behavior.
It is most likely that the natural eunuch was the first category:

12A: For there are some eunuchs, which were so born from their mother's womb:

and likely included homosexuals.
This group:

12C: and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven's sake.

If Jesus was not married, then he was a eunuch. If his genitalia was mutilated he could not enter the temple. If the church’s definition of “born that way" was hermaphrodites, then Jesus could not be either “born that way” or “made that way”. This only leaves “made themselves eunuchs” as an option for Jesus. “Made themselves eunuchs” can only mean one of two things---actually had themselves castrated, or had no interest in women. Either way, in Jesus time, it was a renunciation of manhood at the least.
In that the church has painted him as celibate, they have painted themselves into a corner.
It all ends with:

12D: He that is able to receive it, let him receive it.

Translate---He that can be married should do so, and he who is a eunuch should accept that. You are what you are.