Agnosticism IS the most dishonest position

[The Grand Nudger]

It's the exact opposite, actually. If moral systems - the products of **reason **- struggle hard to rule out rape, infidelity, utilitarianism, etc. then they are a miserable failure. 

Well then, if they don't...they aren't. 

I'm guessing that you believe that islamic morality is rational, right?  It's important to acknowledge any points of agreement between us.  We both put a high premium on any moral system being rational.  We even put a high premium on deciding these matters conversationally when we predicate our statements with a conditional like if.  

Seeing as how this is the case, objections as to the applicability and efficacy of reason..between us...simply aren't genuine.

Again, once you tell me infidelity might not be wrong in some obscure corner of your moral system, we're done. You're advocating for the exact sexual depravity my religion - all religions, actually, came to stand up against. 

Correct, I'm telling you that in a harm based moral system - if an open marriage is not harmful - then it's not wrong.

There may be other morally relevant facts.  Maybe we can take harm away and an open marriage would still be wrong.  It's up to you to suggest what those other relevant facts might be, if you wish to contend....as you do...that infidelity is wrong as a matter of fact.

I think I already explained how these examples are not relationships. Call them open prostitution, orgies, whatever. Leave the word relationships out of this swamp.

Why would I?  On account of the simple fact that those peoples very existence is deleterious to your objections?   Tough luck.  They exist.  See above.

Do you see the irony in your complaining about other peoples moral systems struggling, yet?

Allowing open "relationships" obviously undermines the value of marriage in its traditional sense.  It's basically an incentive to be less committed to one's spouse. Again, if you moral system struggles with that, it's a miserable failure.

-and yet people in open relationships can be as and even more committed to their spouses than people in a "traditional marriage".  

As I keep explaining to you, my moral system doesn't struggle with any of this - you struggle with it.  We both already agree that a harmful relationship is bad.  I'm asking you to consider an open relationship that is not causing harm.   

What would be bad about that relationship?