Shrimad Bhagavatam 3.20.26:
pahi mam paramatmams te
presanenasrjam prajah
ta ima yabhitum papa
upakramanti mam prabho
upon translation:
"Lord Brahma, approaching the Lord, addressed Him thus: My Lord, please protect me from these sinful demons, who were created by me under Your order. They are infuriated by an appetite for sex and have come to attack me."
Meaning:
It appears here that the homosexual appetite of males for each other is created in this episode of the creation of the demons by Brahma. In other words, the homosexual appetite of a man for another man is demoniac and is not for any sane male in the ordinary course of life.
"Foolish and sinful men engage in all forms of sexual intercourse without a female womb, forcing themselves upon other men. They are born again without their organs as neuters." (Mahabharata 13.145.52)
Lord Brahma then gave birth to the demons from his buttocks, and they were very fond of sex. Because they were too lustful, they approached him for copulation. (Srimad Bhagavatam 3.20.23)
ye tu muuDhaa duraachaaraa viyonau maithune rataaH
purushheshhu su dushhpraGYaaH kliibatvaM upayaanti te
pashuu.nshcha ye bandhayanti ye chaiva guru talpagaaH
prakiirNa maithunaa ye cha kliibaa jaayanti te naraaH
upon translation:
"Those foolish men of evil conduct who engage in all forms of intercourse, taking advantage of improper wombs, and forcing themselves upon other men (pumsaka), are born again without their organs as neuters." (Mahabharata 13.133.51-52, Pune critical edition (incomplete text), MBh, Anusasana Parva, part 2, section CXLV, p. 313 (Ganguly edition, complete text)) The word "viyoni", or improper womb, refers to the womb of another man's wife, the mother, sister, animal or child.
A twice-born man who engages in intercourse with a male, or with a female in a cart drawn by oxen, in water, or in the daytime, shall bathe, dressed in his clothes. (Manusmriti 11.175)
Striking a brahmana, smelling obnoxious items such as liquor, cheating, and engaging in intercourse with a male, are declared to cause the loss of caste. (Manusmriti 11.68)
Dharmic sex means in marriage, to conceive children (BG 10.28). This way God has designed it. Anything else will bring negative karma and suffering. It is not a question of human (in)tolerance in a particular society or environment. One of homosexual mentality who cannot adjust to normal marriage can remain celibate, which will be a great blessing for him or her.
My reasoning:
The world is degrading to the lowest status, even less than animal. The animal also do not support homosexual. They have never sex life between male to male. Hence these people who engage is this kind of behavior are less than animal.