A great place to start this conversation is with Catholic moral teaching.

What does the Church teach and why does it teach it.

And keep at bay the first wave of reflexive comments like this one:  "The only reason the Church teaches this is to keep the misogynistic male hierarchy in power...".

Those sorts of points just cause unraveling, disordered thought, and much heat. 

So let's begin with the moral law and why it's designed to bring about our greatest good.