Interesting point. I am not sure but I have had this thought:
Back in the 1920's E. Stanley Jones wrote something to the effect of, Christ did not come to abolish Judaism but to fulfill it. Jones when on to build a case challenging the colonialist missionary movement of his day, arguing that Christ didn't come to destroy Hinduism but to fulfill it, ...to fulfill Islam, ...to fulfill Buddhism, etc.
This has me thinking again about our reading of the Palmers book, "Jesus Sutras", Bjork’s "Unfamiliar Paths", and Oleksa's "Orthodox Alaska".
What if in the name of Christ we sought to preserve and fulfill the beauty of God seen through other religions? While always nudging toward Christ. Like if Saddam Hussein began to follow Christ, should he renounce Islam and become a Methodist. Or could he live Christ in Islam?
This may come as a surprise to some who have visited my site before but I think part of the "image of God" may be about gender, or better said may be about difference.
If we hold to the image of God as the "possession" of the individual then certainly the image cannot about difference (gender etc). If however, we understand the self to be intrinsically relational, so much so that we bear the image of God in relationship (See Grenz, van Huyssteen, Shults, and Janzen), then it may be precisely in our difference (including gender) and our choice for oneness that the image of God is manifest.
It may be that in this way we most reflect a God who is plurality and oneness. We have very real differences and yet are one.
I see every interpersonal relationship as "image bearing" (the plurality and oneness). Anytime "self" is served, we witness "the fall" (in varying degree) of relationship; while anytime we see self-emptying, we see God's dream incarnated.
But I don't limit this to marriage, it's just that marriage has been one of the most approachable human examples of this divine reality, (though that may be changing).
One of the reasons why marriage is such a great Trinitarian example is that the fruit of its love is so tangible. Two unique selves come together forming an "us." The spirit of love is infinitely creative and desires to share its love beyond its perichoretic self and a child is born.