The claim that homosexual marriage would not hurt anyone is not true although I can see on the surface why it would seem to be. Actually, the effects of anything positive or negative are not isolated. Everything we do affects everything else even if the effect is minuscule enough not to see it on the surface. However, in the case of same sex marriage, the effects are anything but small. Legalizing homosexual marriage and normalizing homosexual behavior hurts religious freedom. There are plenty of examples to support this already. One that has been in the news is a bakery that refused to sell a wedding cake to a lesbian couple. Rather than acting like adults and just finding another bakery, the lesbians sued the bakery owner on the basis of discrimination. The owners of the bakery could face heavy fines for exercising their religious freedom by not enabling sinful, soul-endangering behavior. This is not an isolated incident either [http://www.foxnews.com/opinion/2014/01/21/christian-bakery-guilty-violating-civil-rights-lesbian-couple/]. Religious organizations that organize adoptions have been forced to close because they refuse to allow homosexuals to adopt. This is another case of violating religious freedom. Legalizing gay marriage is just another step in the direction away from religious freedom in the public square.
There are also the mental health problems and disorders related to homosexual behavior. Depression and suicide can result. “Many homosexual activists point their finger at homophobia as the cause of these disorders, but the most extensive studies have been done in the Netherlands and New Zealand where homosexuality is widely accepted. In an interview with Zenit News, Dr. Richard Fitzgibbons, a child and adult psychiatrist in practice for more than 27 years, said, ‘Compared to controls who had no homosexual experience in the 12 months prior to the interviews, males who had any homosexual contact within that time period were much more likely to experience major depression, bipolar disorder, panic disorder, agoraphobia and obsessive compulsive disorder. Females with any homosexual contact within the previous 12 months were more often diagnosed with major depression, social phobia or alcohol dependence.’ He concluded by saying, ‘Men and women with a history of homosexual contact had a higher prevalence of nearly all psychiatric disorders measured in the study. These findings are the result of a lifestyle marked by rampant promiscuity and an inability to make commitments, combined with unresolved sadness, profound insecurity, anger and mistrust from childhood and adolescence’” [http://catholiceducation.org/articles/homosexuality/ho0088.html] In fact, it is that promiscuity and inability to make commitments that have led some to conclude that HIV/AIDS is a gay disease. I would stop short of calling it that because so many people with normal desires for men and women also suffer from the disease because of similar promiscuity and lack of respect for monogamous male-female marriage, but there is something to be said for the increased risk between homosexuality and HIV/AIDS nonetheless [http://www.cdc.gov/hiv/risk/gender/msm/facts/index.html]. All of these facts pale by comparison to the spiritual impact, which can lead to eternal consequences.
Homosexual activity is a learned behavior, not a genetic orientation. There is a reason why all the parts work the way they work and produce what they produce--or perhaps I should say reproduce what they reproduce. They are designed for each other and only for each other (Genesis 2:18-25; Matthew 19:4-5). In all of the major studies touted by pro-homosexuality supporters, the authors of the studies had an interest in the outcomes turning out the way they did. Furthermore, those studies have been sufficiently challenged by other scientists. Simon LeVay’s conclusions after his study of corpses that revealed differences in the sizes of hypothalami between male homosexuals and heterosexuals failed to take into account the brain’s neuroplasticity--that the makeup of the brain can change based on how it is used. Said another way, “For as he thinks within himself, so he is” (Proverbs 23:7 NASB). So if a person entertains homosexual thoughts, it would only make sense that a study of their brain would reflect that. Dr. Dean Hamer’s “gay gene” study is disputable on the basis that his sample size was too small while other studies with larger sample sizes produced conflicting results. There is no legitimate reason for anyone to believe that homosexual behavior is genetic or that it cannot be changed. Again, even if someone through some type of generational curse or long-term behavior that changed the makeup of their brain so that they are bent toward homosexual desires, that does not mean they are powerless to change, especially when the divine power of God is introduced. He is the solution to all sins and it is only in Jesus that true transformation can occur.