Summing up my position (and what I think is close to Horton's): Homosexual "marriage," no. Contractual arrangements between individuals, already permissible. But no special status bestowed by society on immoral relationships.
I may only bless what God has blessed from the dawn of creation!
Genesis 2:18
In general: including, for example, contracts between several people or blood relatives. Singling out homosexual partners from the mass of all other perfectly legal partnerships, -- which would happen if the campaign were strictly for domestic unions as a gay alternative to marriage, -- would be singling them for a legal preference precisely for the sexual aspect of their partnership, absent in all other kinds.
But the Christian doctrine clearly speaks against sexual impropriety which homosexuality certainly is.
So therefore, while a Christian organization may generally approve or be neutral to contracts in general, it surely must be opposed to homosexual partnerships even when they are not termed to compete with marriage in the legal space.
Am I wrong?
Sadly, some folks don't want to follow what comes naturally, and shat is the elemental cornerstone of God's creation.
They foolishly strive to create a "special" status for their unnatural behaviors, and will expend every ounce of their life's energy on forcing everyone else to accept and encourage their behavior.
It is sad to watch.
They should be prayed for, in the hope that they can turn to God, confess their sins, receive Salvation, strive to act as Jesus instructed, and spend the remainder of their days in service to their Creator.
The alternative (remaining in denial, and continuation of their sin) is not a path anyone should take.
People in my Reformed circles have been accusing Dr. Mike Horton, Dr. David Van Drunen, Dr. R. Scott Clark and Dr. Daryl Hart for some time of having adopted their “Two Kingdoms” viewpoint out of Lutheran church-state theology. I simply don't know enough about Lutheranism on this point to comment intelligently.
I would be quite interested in reading the material you've written. I think a LCMS Freeper with a long history here will have credibility. I think it may also help me understand the Two Kingdoms theologians better.
My view for a long time has been that Christian conservatives need to take allies where we can get them and not divide into minuscule camps fighting each other. If we're in agreement on most areas, let's work together on those areas and politely discuss the rest.