Christianity has no copyright on marriage.
It exists in many cultures so the definition of marriage is not dependent on Christian views.
Ancient Greece and Egypt, for instance, had wedding customs way before Christianity existed. Other major religions have wedding ceremonies as well.
There are many different definitions of marriage. Some include a religious ceremony, others only a legal contract. In many cases marriage has many other purposes other than love or sex as well.
Financial purposes are common, for instance.
In all definitions I am aware of it is a recognized union between two individuals, so I suggest you focus on that.
I also suggest religious views should be ignored in this discussion entirely as there is no common ground.
It would be more productive if the religious people use their religion's explanation for why homosexuality and gay marriage are wrong instead.
I personally think that many people are opposed to homosexuality because they cannot picture themselves being with individuals of their own gender.
There are many examples of similar things. Some people eat dogs. Other people are disgusted by that and think negatively of the people who do eat dogs. Now that's obviously overly simplified and not true in many cases. I just want to point out that because some people find something disgusting it is not inherently wrong.
Banning homosexuality or limiting the rights of homosexuals is basically discriminating groups of people for who they are. Homosexuality cannot be treated or changed into heterosexuality.
Homosexuals do not harm others by being who they are.
I see no moral reason why homosexuals shouldn't have the same rights as heterosexuals.
The only objectively correct fact I have seen anti-gay people propose is that homosexuals do not make children if they are allowed to be who they are. Seeing as humanity is already overcrowding the planet and we are going to reach the maximum capacity of our habitats at some point in the near future I do not think that is a good argument to make.
Last edited by Redundant; Feb 16, 2015 at 01:36 PM.