[The posts and comments to which this post is a response may be found here.]
Good. I’m glad you recognize Christian scripture. Here’s the punch line.
One does not need a reliance upon any religion’s custom, scripture, or received wisdom to reason the social purpose of marriage. Implying rejection of gay marriage requires religious belief is vulgar.
Marriage is about securing the welfare of children. If you believe that so-called gay marriage provides for the welfare of children, then we have far too much to discuss than can be accomplished within this medium. I will, however, address your assertions regarding infidelity.
Infidelity in marriage is not a problem for independent self-supporting adults; any argument contrary requires that the victim of infidelity is either not capable of independence – and thus not capable of competence to contract a marriage nor an equal partner to a marriage – or relies upon the victim’s exposure to risks inherent to intimate body fluid contact such as disease transmission. Infidelity is a problem for children who rely upon the undiluted support of a father and a mother. An infidelity in a sexual partnership exposes the children of that partnership to risks associated with “brother by another mother” arrangements. So-called gay marriage is a union of adults for the welfare of adults. Every court case I’ve read asserts access to tax benefits for the welfare of the surviving spouse – not for the children of the couple – because the same-gender couple cannot conceive children. Child support justly conveys from a parent to a child; alimony from a former spouse to a spouse for breaking an agreement related to child-rearing. Thus you found your argument regarding infidelity upon a false premise: the infidelity of playmate for habitual erotic non-sexual encounters. Marriage is not meant to provide some kind of official sanction to erotic encounters, habitual or singular. Marriage is meant to provide sanction to sexual relationships whose purpose is conception and provision of children. Attempts to provide exceptions for instances of adoption and remarriage specifically address breakdowns within this social system with patches meant to provide the closest facsimile possible for ideal marriage conditions. Thus, adoption of children is meant to ameliorate (it cannot correct) the conditions for orphans in fact or in practice, and remarriage is meant to correct provisioning and custodial challenges faced by a lone unmarried parent. For both these exceptions of adoption and remarriage, infidelity remains a problem for children because adults unable to support themselves are not competent.
The path to effective social systems is narrow, and the gate through which marriage must pass is a lifelong commitment to your partner in conception. Misapplication of the word, “marriage,” to non-sexual co-habitations cannot conceal this social purpose, no matter what examples of bureaucratic discrimination you muster. Such discrimination is wisdom.