That blog uses horrible argument. Slippery slope fallacies all the way. Here again we get religious fear-mongering used to influence people politically.

Lets look at their conclusion:
So, here is the future: if the state can declare the Johns unfit to be foster parents, and thus deny them foster children, because they may teach these children the Christian understanding of human sexuality, then the state, armed with Judge Walker’s premises, can declare any married couple unfit to be parents, and thus remove their natural children from their home, because these parents, in fact, teach their children the same lesson the Johns were forbidden from teaching.
Slippery slope anyone? Child Protective Services do not remove children from homes lightly. My gf's mom has recently gotten severyly depressed, and her young sisters are in an amazingly oppressive atmosphere. They are 12 and 16, but they are not allowed out of the mom's sight. They sleep in the same room, despite living in a 4 bedroom house, she doesn't let them go to school, she doesn't let them out of her sight at all. Child protective services were called, and investigated, but since there was no physical abuse going on, CPS couldn't do anything.

If CPS isn't doing anything in this situation, they certainly aren't going to take someone's children away because of their beliefs on homosexuality.

Secondly, they weren't denied because they are christian like the article tries to emphasize, but because they declared that they are intolerant toward homosexuality (and there are plenty of Christians that are fine with homosexuality). I think the adoption agency has the right to impose this restriction, just as they would not want a foster home to be one that teaches white power, or that man are superior to women and women belong in the kitchen.