Many of those groups insist in the sinfulness of homosexual behavior. Here you have a quote from the Recall group, you can find this in the section of their website called: Faith Positions:
A homosexual orientation is usually not chosen and is a cause of suffering. Although this inclination is objectively disordered, it is not in itself sinful. Homosexual behavior, in contrast, is gravely sinful (Rom 1:26-27; 1 Cor 6:9). Like all human actions, homosexual behavior is a choice, because we are not animals dominated by urges, but persons with free will. Like everyone else, homosexual persons are called to chastity, that is, the right ordering of their sexual desires.
Note that they say homosexual inclination is "objectively disordered." This statement contradicts the opinion of most medical and scientific associations, as you could see in Just the Facts About
Sexual Orientation & Youth: A Primer for Principals, Educators and School Personnel, but that's not the point now.
These groups also insist in the inherent risk of homosexuality as a cause for disease, specifically HIV/AIDS, and they are against the scientific fact that is not being homosexual in itself what is a cause for disease, but that specific kinds of sex (such as unprotected anal sex) are riskier than others (that would apply to heterosexual anal sex too). From this it follows to them that homosexual sex is a risk factor.
Then it must be only homosexual sex among men, because in fact, homosexual sex among women has extremely lower risk (NOTE, PLEASE, THAT IT DOES NOT MEAN THERE IS NO RISK!) than heterosexual sex.
Is it that God's perceive homosexual sex between women as less sinful than between men?
Or is it that the level of risk has nothing to do with having homosexual or heterosexual sex, and a whole lot to do with having unsafe attitudes towards sex and life (being promiscuous, having unprotected sex, being unfaithful, using drugs, etc.)?
Homosexuality in itself does not lead to promiscuity (and the huge amount of adultery out there should send a signal on the issue). There are many couples that has been together for many years, and has much lower risk of contracting any STDs than many unfaithful married people.
So, how do you explain now the low incidence of HIV/AIDS transmission among lesbians? It has to do with the technicalities of lesbian sex, obviously. Therefore, it is not being homosexual what is risky.
Oh, did I forget to mention the source of this? Well, take a look at this Fact Sheet about women who have sex with women from the National Institutes of Health... That gay advocacy organization.
Female-to-female transmission of HIV appears to be a rare occurrence. However, case reports of female-to-female transmission of HIV and the well documented risk of female-to-male transmission of HIV indicate that vaginal secretions and menstrual blood are potentially infectious and that mucous membrane (e.g., oral, vaginal) exposure to these secretions have the potential to lead to HIV infection.