You are inventing Biblical teaching to suit your own prejudice.  For the most part, marriage in the ancient world of Palestine and in the days of Jesus' physical presence on earth was all about ownership of property, lines of inheritance and the recognized status of the land-owning, ruling class of a carefully defined economic and ruling class of men.  The Bible DOES NOT teach marriage as being between one man and one woman in a covenant of exclusive, spiritual, and legal mutuality as well as an expectation of sexual fidelity.  Those definitions came much, much later well after the death of Jesus.  And as for the quotes from Mark, you may want to do a little investigation into the context(s) in which His comments were made and the cultural practices - both Jewish and secular - of the times.  Marriage - and that includes ssm - as we know and practice it today were not in existence at the time of Jesus or Mark or Paul.  It is not the homophobia of Jesus we are concerned with, but yours.