Regardless of your position on The Law, The Law doesn't condemn Homosexuality.
I actually want to start by saying I don't really approve of how the Leviticus verses are commonly written off by other Pro-Gay Christians. Not all of Leviticus is purely ceremonial law. So mocking the idea of Christians citing Leviticus 18 as if it's comparable to "don't boil a kid in it's mother's milk" or eating shellfish is just setting yourself to look Biblically illiterate. The main Leviticus verse cited on this subject isn't in the same section as the dietary laws, it's sandwiched between verses on child sacrifice and bestiality. Both things no Liberal would view absurd to consider a Sin, but the latter we would have no Biblical basis for condemning if we went only by the New Testament. Same with the earlier Incest laws.
Don't misunderstand me, Christians aren't under The Law in my view, not even the Decalogue (what we commonly call The Ten Commandments) we're under the New Covenant where God's Law is written on our hearts. My point is however is not all Leviticus verses are on the same level, and all of Leviticus could still be useful to help guide Christians, even the dietary laws which had good health reasons behind them.
So what's condemned in Leviticus 18 I do view as a sin, and as much a sin now as it ever was. But I don't view it as a blanket condemnation of all Homosexual, Homoerotic or Homo-romantic affection. Thing is I feel the New Testament references I'll need to discus latter are drawing on this Leviticus law, so Leviticus needs to be understood here.
"As with a Woman" is a qualifying statement. So the broadest possible application is that it condemns male on male penetration.
Rashi (1040-1105)... in his commentary on Leviticus 20:13 explains that “as one would with a woman” means “if he inserts [sc: his membrum] like a stick into a tube” (a quote from the Talmud, Baba Metzia. 91a) which refers to an applicator inserted into a tube of kohl.
You'll find it here http://www.chabad.org/library/bible_cdo/aid/9921/jewish/Chapter-20.htm#showrashi=true
The other Leviticus chapter in question is 20, and that one is absolutely not something relevant to New Testament believers in terms of life style. (I won’t call it completely irrelevant because it’s still part of the Inspired Word of God.) Any passages that includes punishments to be carried out for the crime are part of the civil law code of the nation of Israel. For many reasons I believe New Testament believers should be more Libertarian then the Law of Moses was. God had a special arrangement with the nation of Israel, even before Christ I believe he would have always preferred less strict civil laws from Gentile nations, thus his approving of Gentile kings like Cyrus and Artaxerxes.
I also believe that on this side of the Cross capital punishment is no longer permitted.
Most people don’t see it as significant that the wording of the alleged condemnations of same sex intercourse are all clearly male gender specific. But I believe what The Bible doesn't say can be important. Leviticus 18:23, the verse on bestiality that immediately follows the verse commonly cited as condemning homosexuality, does risk sounding redundant to make it absolutely clear that both men and women are forbidden to lay with animals. Yet verse 22 only appears to refer to "men lying with males", no female equivalent. So logically in my view we have two options, either women are allowed to do something men aren't, or the common modern understanding of the verse is incorrect. While there could be good reasons to argue for the first option (and I'm surprised more people haven't), I feel the second is the correct one as I shall explain.
There are two sections to Leviticus 18. The first section is sexual sins, mainly incest but a few others are addressed. Then the focus shifts to Idolatry. Here is the thing, verse 21 is where the change of subject occurs. So while the first two verses after that do have a sexual element to them, it’s not as sexual sins they're being addressed but as idolatrous sins. And that is key to understanding them.
The KJV rendering of Leviticus 18:22 is “Thou shalt not lie with mankind, as with womankind: it is abomination.” Before I get into studying the text, I want to point out that even in this English rendering, "as with Womankind" is clearly at most specifically only referring one specific kind of sex act, penetrative intercourse of some form. ( "lying" alone in Biblical terminology would be enough to imply we were dealing with something sexual.) It means the one thing men can do together that can be seen as an imitation of the unique sex act only a man and woman can do.
Now bare with me because I’m going to have to break down pretty much every word here.
The first word I’ll address is actually the last, "Abomination". Abomination has become a very loaded word in modern English, being commonly used in Frankenstein type Sci-Fi stories to basically mean a raping of nature itself. And this connotation is what’s meant by how the word is commonly emphasized when certain people quote this verse. A number of Hebrew words are translated abomination, none of them mean unnatural or anything like that, they're all about idolatry. The “Abomination of Desolation” uses a noun that is clearly a Hebrew derogatory term for an Idol itself, but the word translated "Abomination" here is more about the acts affiliated with worshiping Idols and how God views them very negatively.
While I rejected above writing off this entire command by comparing it to the dietary and other ceremonial laws. I do think it's valid to address the over emphasis on the word Abomination here by pointing to how it is also used of those kinds of restrictions in the Torah. Leviticus 11:12 "Whatsoever hath no fins nor scales in the waters, that shall be an abomination unto you." Technically that one is a different word in the Hebrew, but to the most absolute of KJV onliers that is irrelevant. Deuteronomy 14:3 does use the same Hebrew word as Leviticus 18 talking about dietary restrictions, there it is translated "abominable thing". It's also used in Ezekiel 43-44 to refer to Uncircumcised gentiles entering The Temple.
I actually think a more accurate translation of the word would be "taboo".
The word rendered "lie" is translated perfectly.
The word rendered "mankind" is Zakar (Strong # 2145), technically accurate, but based on the first time Zakar is used (Genesis 1) I personally would translate it male or masculine. The word translated "womankind" is ishshah (Strong # 802), again technically accurate but I’d just render it woman, it is also the word for wife. Both are gender identifying words, as you’d expect, but the thing is they're not their main counterparts to each other. Zakar is usually paired with Naqebah (Strong # 5347) including when it‘s first used in Genesis 1:27. Which I would always translate female. And ishshah is the feminine form of iysh (Strong # 376) which is translated both man and husband. Technically none of that makes a drastic difference in the meanings of the words used, but I feel if the gender distinction was all God was concerned with here, he would have been more consistent in what terms he used.
The word translated "with" is Mishkab (Strong # 4904), in the verse in chapter 20 this is rendered "lieth". And both those renderings are off, they're not even the right kind of word, it’s a noun not a verb. Of the 46 times the word appears in the Masorectic Hebrew text, 34 of them the KJV accurately translates it bed, 4 times it’s rendered bedchamber and once it’s rendered couch. The two Leviticus verses supposedly about Homosexuality are simply two of 7 verses where the KJV translated it as a verb.
I’m not of course the first person to question the common interpretation of this verse, but my approach is different from many. Some have suggested the real intent here is to condemn a husband making love to a male in his wife’s bed. Because in the ancient world the bed in which a married couple made love was considered the wife’s bed, her property or domain. Such concepts do carry over into medieval and renaissance times, you see it on The Tudors in fact. I don’t believe that’s the main concern here, but it is possibly relevant.
Now I refer everyone back to the last section of the Sodom and Gomorrah post. What I and many scholars believe is that what’s in mind here is the same practice being performed by the Qadesh male temple prostitutes. The context of idolatry to these verses already established makes that likely, but here is the thing. Specific details of the ceremony often involved the prostitute dressing in female clothing like it was her wedding night, and engaging in the sexual act in a sacred bed said to be the bed of Astarte.
Now for Leviticus 20:13 “If a man also lie with mankind, as he lieth with a woman, both of them have committed an abomination: they shall surely be put to death; their blood shall be upon them.” The part I put in italics is different in how the KJV renders it, but in the Hebrew is basically identical to 18:22, so just copy and paste everything I said about that. I also already addressed the death penalty aspect.
The word at the beginning rendered "man" is iysh. That word is sometimes translated Husband, I've heard some some suggest you have to be married for it to apply but I don't feel quite convinced of that. I know one website online dedicating to arguing this is only about Adultery, I don't feel that works with my understanding of how The Bible defines Adultery.
So while homosexual intercourse is relevant, It’s more specific then that. The context is describing a Pagan ritual. To some being involved in a Pagan ritual is enough to condemn it altogether. In my view that's flawed logic, Pagan rituals did many things, including many things very much the same as the Israelites did in worshiping YHWH. Skeptics of the Bible like to point those things out to say the Israelites just grew out of the Canaanite culture. That claim doesn't hold up of course.
The Law does condemn many things specifically citing usage in Canaanite rituals as the reason. Most notably that the Israelites were NOT to build altars to the LORD on High Places (mountain tops or hill tops). But in Ezekiel 40-48, when Paganism no longer even exists (and clearly the very geography of Israel has changed) God's Temple is on a High Place. But this command doesn't make doing anything on a High Place a Sin, acts of Worship even of the True God are advised against there. But it's not a Sin to build a house on a hill top, or to even walk on one. It's just about how to properly worship.
Leviticus 18:24 and to the end of the Chapter clearly defines the earlier commands in those same terms. "Defile not ye yourselves in any of these things: for in all these the nations are defiled which I cast out before you: And the land is defiled: therefore I do visit the iniquity thereof upon it, and the land itself vomiteth out her inhabitants."
But you may be thinking, "in that case isn't beastiality in the same position"? An animal can't consent to sexual relations with a human, beastality is therefore inherently an act of Rape. So even if there never was a single Bible verse specifically on it, Christians should consider it wrong for the same reasons any other act that is abusive to animals is wrong.
At the most, you might might be able to convince me it's condemning Anal sex. It is only that form of male on male sex that is viewed as imitating the unique act only a man and a woman can perform. Society has a tendency to view anal sex and male homosexuality as synonymous. But this stereotype is in fact a very flawed assumption, and some studies have shown that only a minority of Gay or Bi men engage in it or like it at all.
Example, Magnus Hirschfeld, in his 1914 work, The Homosexuality of Men and Women, reported the rate of anal sex among homosexual men surveyed to be 8%, the least favored of all the practices documented. (William A. Percy and John Lauritsen, Review in The Gay & Lesbian Review, November–December 2002) Likewise, some scholars state that oral sex and mutual masturbation are more common than anal stimulation among gay men in long-term relationships, and that, in general, anal intercourse is more popular among homosexual male couples than among heterosexual couples, but that "it ranks behind oral sex and mutual masturbation" among both sexual orientations in prevalence. By the 1950s in the United Kingdom, it was thought that about fifteen percent of male homosexuals had anal sex. Other studies very, some about 50/50 and some more recent ones do imply a majority do it, (as if it's popularity has been increasing, perhaps simply from society telling them their supposed to do it). But all clearly have a large number who do not.
Many Christians view how the risk of HIV and other STDs are higher with Gay men is itself proof that something is wrong with it. Of course they ignore that those same statistics have Lesbian intercourse as far less risky then Heterosexual. At any rate those statistics are flawed, being in part skewed by gay men being more likely to get tested because they believe their at a greater risk. And the degree to which it is the case is only because of the Anal sex as I discussed above, which does have other health risks too.
But that is a big maybe. I stick to my argument that it is the Pagan ritual sex being condemned here. Which contrary to what you might assume does still go on today, in different ways but it does.
In the 1970s and early 1980s, some religious cults practiced sacred prostitution as an instrument to recruit new converts. Among them was the alleged cult "Children of God", also known as "The Family", who called this practice "Flirty Fishing". They later abolished the practice due to the growing AIDS epidemic. (Williams, Miriam (1998). Heaven's Harlots. New York: William Morrow/ Harper Collins. p. 320.) In Ventura County, California, Wilbur and Mary Ellen Tracy established their own temple, "the Church Of The Most High Goddess", in the wake of what they described as a divine revelation. Sexual acts played a fundamental role in the church's sacred rites, which were performed by Mary Ellen Tracy herself in her assumed role of High Priestess. Local newspaper articles about the Neopagan church quickly aroused the attention of local law enforcement officials, and in April 1989, the Tracys' house was searched and the couple arrested on charges of pimping, pandering and prostitution. They were subsequently convicted in a trial in state court and sentenced to jail terms: Wilbur Tracy for 180 days plus a $1,000.00 fine; Mary Ellen Tracy for 90 days plus mandatory screening for STDs.
"Hieros gamos" (holy marriage) and "Sex Magik" also exist in modern Neo-Pagan and occult movements, just search for those two terms on Wikipedia. As a Libertarian I disagree with such activity being criminalized, on among other things First Amendment grounds. But to a Jew or a Christian it is sinful, being a violation of the first two commandments, and something we should not do.