There is a point at which diametrically opposed positions make it impossible to fellowship.
I couldn't have said it better.
I wonder how the Finns reconcile their stance on homosexuality with their Christian faith?
Exactly. And why is this “fellowship” so needed? Would they be having “dialogue” with Shintoists? No and for obvious reasons. Truth does divide and having Biblically orthodox views on matters such as sex, marriage and the family will require the group that wishes to remain Biblically orthodox not to fellowship with groups that oppose that.