text: Not "entirely from the perspective of social science", but more importantly from a growing consensus and public consciousness. You seem to acknowledge this yourself as "generally considers equal treatment of LGBT people in terms of justice". This is somewhat distinct from a more esoteric or academic "social science". 
  You also give too much credit to the church. To adopt your terminology they don't "entirely"  "approach the subject in terms of scripture and tradition". Rationalize yes, but also upon the more recent defensive construct that still refuses to de-link homosexuality from clerical sex abuse, maintaining and capitalizing upon the debunked myth. This in addition to what you rightly identify as tradition:  the sexual complementarity model revived by Pope John Paul, which in turn supports the "spousal" argument for the exclusion  of women, not to mention the reproductive politics of sex, etc. Too much vulnerability to seek common language with LGBT let alone honest discussion.