That's because they don't, actually, believe there's anything wrong with adults having sex with children.
It’s all about the perverted destruction of church and family. Gay “marriage” is only a step, not the end. Polygamy and pedophilia are next on the list, to be followed by incest, bestiality and necrophilia. The term “marriage” will be so devoid of meaning our grandchildren will be able to “marry” household appliances.
The end game is to deny that we have souls and make us pieces of meat to be disposed of as the state sees fit.