Of course we should use reason and rational debate. In my experience, reason almost always supports the ethics of the Judeo-Christian tradition.
I find it hard to answer the second part of your question because you seem to assume these two approaches are mutually exclusive when they are not.
But I will say this. Personal taste cannot completely be eliminated from the analysis. We can only make a reasoned argument from certain premises that we hold. Many of those premises are supported by other arguments, but at some point, we must just accept certain premises as self-evident. In the Judeo-Christian tradition, we believe that God wrote these basic truths on our hearts.
There are certain things that we just all know to be true by intuition. The existence of other "opinions" usually is the result of self-interested blindness. On some level, we all know that the world would be a much better place if we waited until marriage for sex. Instead, we go ahead and have sex outside of marriage and then abort the resulting fetuses. But we concoct arguments to justify it because its convenient and it feels good.