I understand specifical scientific ways that homoloveuality would be troublesome for the homoloveual, (No procreation), and such-- but that's just about it, the only major thing that homoloveuality actually does is not allow reproduction, this further leading to the family possibly becoming non-existant in a few years unless they have another straight son/daughter to actually be able to continue their line, but that's seriously it-- nothing more and nothing less.
Gay Marriage is honestly the least of anybody's problems, and don't give me that 'When we face god in the end, we will see who is right.', the world has bigger fish to fry than say, a male getting married to another male, Terrorists are running rampant, Ebola is once more a danger and many countries are having economical issues-- I highly doubt any Christian would care if somebody got married to another dude and was happy, sure the word of 'Christ' contains that homoloveuality is a sin-- an abomination, as I believe it describes, but honestly-- would any logical Christian who doesn't act like an starfish and does not follow the Bible's word to the letter actually care about this.