Whats the real excuse for oppsing gay marriage?

so people oppose gay marriage because the bible says its wrong, but what r u 2 say its wrong or right. the bible was written by mankind. so who r we 2 say what is wrong or right in the bible. Don't get me wrong im a devoted christian but honestly i asked my pastor how do we know what is right & wrong in the Bible & he told me its not important whats wrong or right because the whole idea is to get a point across so you get an idea of events that happened. So the people who put together the bible were the deciders of what to put in it and really how do they know what is made up and what isn't. So don't tell me that the bile says because the bible is not 100% accurate. Maybe if it was written by god himself but like i said it was written by mankind who has varying opinions on different subjects. so basically my question is why do you really oppose gay marriage and not because the bible says so. also i kn ow some people think its disgusting but really is it? Love is love so what doe sit matter who shows it to whom? You only think its disgusting because u don't want other people to ume u r gay. if not prove me wrong. Finally its jsut like slavery where people r ridiculed because they are not like other people, how to you c that as being right or just.