Supporters of gay marriage have been met by a noisy resistance outside the Scottish Parliament on Thursday (8 December).
Members of the Humanist Society had gathered at Holyrood the day before a Scottish Government consultation on the issue closes.
But they were at times drowned out by religious supporters of the institution of (straight) marriage.
Ross Wright, of the Humanist Society told the crowd: 'Marriage should be a free choice: free for all couples and free for the celebrant to choose whether they are happy to officiate. Marriage is important. Love does not discriminate and a concept of modern marriage for Scotland is the sensible and reasonable way forward.'
As he spoke, one minister began preaching over a loud speaker.
The two sides, separated by police lines, then began to try to shout over each other. The humanists were told to read the Bible, while they in turn branded their opponents homophobes.
Donald Morrison, a Free Kirk elder from Inverness who organised the counter-rally, said: 'It is not for the Scottish Government to change marriage. This is non-negotiable. We will never bless same-sex marriage. The foundation of marriage is already in place. It's God's law.'
The Scottish Government launched a consultation in September asking if marriage in Scotland should be allowed for gay people through a civil or religious ceremony.
Same-sex couples can currently enter a civil partnership which carries full legal rights but the ceremony cannot be conducted in a church or other religious premises.
This comes a day after Equal Marriage campaigners have handed over 18,000 responses to the government's consultation which ends on Friday.