The only legitimate secular argument against homosexuality is that homosexuals are biologically useless since they don't reproduce. However, in a massively overpopulated world, it really doesn't matter in the slightest if a tiny percentage of the population doesn't reproduce.
Not to mention, the most prolific pedophiles are usually devoutly religious types, not pride parade types. Most sex offenders in prison are conservative Christians who rape children while they simultaneously condemn homosexuality and drink the AIDS-infected blood of Christ.