Recently, a very Modern Rabbi appeared at a ceremony celebrating the union of two males [about which the Torah writes - וְאִישׁ אֲשֶׁר יִשְׁכַּב אֶת-זָכָר מִשְׁכְּבֵי אִשָּׁה - תּוֹעֵבָה עָשׂוּ שְׁנֵיהֶם; מוֹת יוּמָתוּ, דְּמֵיהֶם בָּם] and blessed the "chatan" and the "chatan". He received a lot of heat for this. One of my friends and readers, based on the approach of Rav Aharon Lichtenstein ztz"l, feels that we should not be so hard on homosexuals. Being haughty and dishonest are also called abominations in Tanach as are other aveiros which cause us much less moral revulsion. Rav Aharon felt that we should have sympathy towards them because they suffer so much [while he is clear that he doesn't condone or permit same sex unions].
However, I don't think that even Rav Aharon would approve of attending such a ceremony and blessing the couple. Also, despite my great respect for Rav Aharon, I have great difficulty agreeing with his approach. I also think we should feel terribly for those who suffer so much. But what the homosexual community is trying very hard to do is to receive validation from society at large for their choices. If they wouldn't flaunt it and just do what they do in private, as was generally the case until not so long ago [when I was younger], then I can accept it more readily [coupled with tremendous pain that Jews are sinning, as am I because כל ישראל ערבים זה בזה]. But it has become a hot button issue for which a war is being waged to essentially erode the classical Jewish family. I am not saying that one should be mean to homosexuals and spit on them. But one must strongly denounce and condemn their attempts to publicly abrogate Torah law and permit relationships that have been forbidden for the 3,300 years since we received the Torah.
Besides that, when the Torah mandates a death penalty that means it is very serious. One doesn't get the death penalty for eating pork or stealing 400 million dollars or chopping off someone's arm or many other horrific sins. It would seem that the fact that it is called an abomination together with the fact that there is a death penalty, compounded by the fact that it is a sin of a sexual nature which is generally more severe, in addition to the fact that our generation is one where almost of the boundaries of propriety have fallen and various other considerations. spells that going to this chuppah [why do they have a Jewish ceremony when Judaism forbids their very union?] and giving them a bracha is FAAAAAAR outta bounds and every bit of criticism leveled at this fellow is justified.
Here is an article about the various איסורים one incurs when attending halachically forbidden wedding ceremonies such as intermarriage and the like. The author [who wrote it together with his son] is a very controversial Modern Rabbi who holds very liberal views on various topics but he nevertheless forbids attending such celebrations on various grounds [you can skip to the end and read the summary].
At this ceremony the mother of one of the men [who looked and sounded very frum] arose and gave an emotional speech of acceptance in support of her son. I have a question for her and all of the other people in favor of these things - do you believe in שכר ועונש?? If you do then if you REALLY care about this couple then how can you celebrate?? Would you celebrate if they were enjoying a drug that will definitely give them cancer?? Would you encourage them if they were enjoying a food that would give them ח"ו Lou Gehrigs disease??
According to the Ramban, one second of gehenom is worse that 70 years of יסורי איוב.
But that is a moot point for a reason which might startle you - In my opinion there are plenty of observant Jews who don't really believe in שכר ועונש. Period. They are not particularly afraid of gehenom and don't really believe that a mitzva will bring them eternal bliss beyond anything this world has to offer.
That is the very sad reality. Hence, religious people can bless a couple doing an avierah and be happy for them. I, for one have tremendous sympathy for them. Eternity is a loooong time. [Some claim that they are אנוס. They were born that way. Yes, maybe they were born with an attraction to the same gender. Maybe. But they weren't born in bed with such a person.]
I would just like to add one more point -
והיה מחניך קדוש!!!