First of all, let me say that I know this is a very delicate issue. In no way should my question be seen as an attempt to endorse negative attitudes towards the LGTB community. I am seeking objective, historical evidence; not speculation or personal opinion.
According to this Wikipedia article, "many forms of religion, including the Eastern faiths and Abrahamic faiths, do not support gay sex. Evangelical Christianity, Catholicism, Mormonism, Orthodox Judaism and Islam hold the view that gay sex is a sin and that its practice and acceptance in society weakens moral standards and undermines the family."
Moreover, according a 2009 report by the International Lesbian, Gay, Bisexual, Trans and Intersex Association, 80 countries in the world consider homosexuality illegal, with five of them punishing homosexual acts with death.
It seems that the movement to push for the acceptance of LGTB rights is recent when compared to a relatively long history of religious and political entities holding negative attitudes towards homosexuality.
What are some of the historical reasons behind this?