Gambling is legal in some venues of the State of California. Do schools teach that it is good? Do churches lose their tax exemptions when they inveigh against it? Does its legal existence affect the parental right to teach children that it is not a good thing? Do I threaten your economic probity if I gamble?
Anyone who has loved another human being knows that it is beyond one’s will to decide whom to love. For society, the high moral ground would be to grant people in loving relationships the ability to solidify their mutual commitment in the eyes of the law with the economic and social benefits that are conferred with the civil act of marriage.
No one will force any church to perform these unions or to stop disapproving of them or even speaking out against them. No one will prevent parents from teaching their own values to their children. Religious and parental values are personal. Since they are not held universally, they belong in the church and the home, not in the Constitution.