To be an activist requires fiery conviction, sometimes in the face of what seem like insurmountable obstacles.

Fifteen years ago, the idea of gay couples being able to form legally recognised partnerships, let alone marry, seemed to many like an impossible goal.

Politicians and campaigners who supported the idea would take encouragement from the example of places such as Denmark, where same-sex partnerships had been recognised since the late 1980s, and from progressive American states like California where the idea of same-sex domestic partnerships was gaining ground. Even so, civil same-sex unions seemed a long way off in the UK and same-sex marriage even further. What polling evidence existed appeared to show stubborn public opposition to the whole concept. Activists kept going because they believed what they were fighting for was right.

If only they had known just how quickly and decisively public opinion would change. Civil partnerships between same-sex couples were legalised in 2004 and now same-sex marriage is well on the way to becoming reality, all with the backing of a majority of voters. The latest YouGov survey on attitudes to gay marriage indicates that 56% of Scots now support the idea. The poll comes just two weeks after the Marriage And Civil Partnerships (Scotland) Bill passed its first stage at Holyrood; taken together, all this underlines that a major improvement in the status of lesbian, gay, bisexual and transgender people has taken place since the millennium.

Perhaps unsurprisingly, the latest polling evidence shows that support for gay marriage drops with rising age: 77% of 18-24-year-olds are in favour compared with 38% of those aged over 60. Over time, the majority in favour may rise still further. Women are significantly more likely to support gay marriage than men and that trend may change more slowly; even so, in both genders and in every age group except the over-60s, more people are in favour than against. What seemed a dream for equality campaigners has become reality.

Quite how the anti-gay marriage campaign Scotland for Marriage has managed to infer from the figures that "MSPs at Holyrood are utterly out of step with the voters", is hard to fathom. The poll does not show that, although a bigger percentage of MSPs support gay marriage than the wider public, according to the survey. The implication among those against gay marriage appears to be that, if a minority of voters oppose a change in the law, then the Government should not change it, even if a majority do support change. That could hardly be described as fair.

That is not to say the views of those who oppose the change should not be respected. A significant minority - 35% - do oppose gay marriage, some because of their sincerely held religious beliefs. That is why it is so important that the bill has balanced the freedom of same-sex couples to marry with freedom of conscience by ensuring that no faith group or celebrant will be compelled to perform gay marriage ceremonies. The UK Equality Act of 2010 will be changed to prevent celebrants facing the threat of criminal charges. Those safeguards are crucial. The guiding principle must be that same-sex couples should be able to marry if they wish and religious groups to conduct themselves according to their conscience, without either imposing their will on the other. Beyond that, the law should not go.

This bill has been controversial but, in time, same-sex marriage will become part of the social and legal landscape. After all, this survey shows that many people greet the whole concept just as they do heterosexual marriage, with nothing more than a smile and a shrug.