The Oregon State constitution has been amended to protect gay rights, according to the article.
I dont know what the Oregon constitution says about same-sex marriage. But it remains that Section 1 of the 14th Amendment prohibits the states from making laws which abridge the constitutionally enumerated rights of citizens.
And since the states have never amended the Constitution to expressly protect gay marriage, Oregon is wrongly using constitutionally unprotected gay marriage rights to trump constitutionally enumerated rights, the 1st Amendment protected rights of religious expression in this example.