It has been suggested that arguments for and against same sex marriage could be summarised by two words (I have added my summaries):

Love – should any couple who love each other be able to get married, regardless of their sexual orientation?

Fear – fear of religious faith being challenged, fear of marriage being devalued, fear of the end of society as we know it, fear of homosexuality?

Someone heavily involved in the debate has blogged:

The contrast between those in favour and those opposed was striking.

There have been strong arguments both for and against the proposed changes in the marriage equality bill. Politicians have received numerous emails and letters, and a large number of people made submissions to the parliamentary select committee.

We looked for a graphic way of representing this contrast, and used a “sample” of all the correspondence that arrived over a particular time to create word clouds. It’s not science. It’s not discourse analysis. But it makes the point.

Fundamentally there is a difference of world view: those opposed subscribe to a moral code based, usually, on a particular religious faith, and believe everyone should follow this code, whether or not they share that faith.

By way of contrast those who support the Bill usually have a very clear pluralist world view, in which they see the role of Government as providing a framework for a society of many faiths and codes of behaviour.

Source.