Why Gay marriage is not marriage

I've been thinking about marriage and in what ways it could possibly
reflect Christ's relationship to the church (see Eph 5).

Here's what I've come up with:

1. Both illustrate what it's like to have a relationship with someone
who will hurt you. What it's like to (try to) remain faithful when the
other person, in big or small ways, will not always be faithful. For
Christ and the church, the relationship is asymmetrical, for us, it's
symmetrical.

2. We, falliable humans, learn from a first person perspective what
Jesus' experience of us is like. He loves us dearly, he admires so many
of our qualities, he loves spending time with us, but we continue to
"act stupid" even though we love him too.

3. Because of this, we learn about grace. To give it, and we learn the
humbling experience it is to receive it.

4. All this, we learn, in the context of loving, someone who is
fundamentally different to us. Christ loving his fallen human-only
church, and us loving the fallen other gender. This is why I'm not a
supporter of gay marriage. As humans we tend to love people who are the
same as us. To love someone who is not only different to you, but
designed to be different from you and aiming at being something
fundamentally different to you gives us a glimpse, (it's deep and rich
experience but still just a glimpse) of what God is like.