I have no reason to doubt that Michael and Jenet Erickson are generally nice people with no malicious intent. However, it does not make them any less ignorant, self-deluded, or bigoted. This couples opinion piece, "Michael and Jenet Erickson: Being for traditional marriage does not mean being against anyone", would be laughable if it did not represent such a prevalent mindset.
There are two blatant fallacies that dominate the whole thing. There is no universally accepted definition of "traditional marriage" and never has been one. Scripture are full of examples of acceptable marriage practices that would horrify the likes of Michael and Jenet. Even if that were not the case it does not matter in regard to US law. Legislating anything based solely on highly subjective religious interpretations is flat-out unconstitutional.
The second problem is that you cannot claim you are not "against anyone" when you are in fact actively seeking to deny the rights of others. You can believe that marriage should be between a man and a woman but when you seek to deny the rights of others you have gone beyond just believing something. Denying other people the same rights you yourself enjoy is harmful and, yes, it is also bigotry.