The ancient Iranian religion of Zoroastrianism is now one of the smallest religions in the world. There are an estimated 200,000 Zoroastrians worldwide, and only about 2,500 living in Australia.

By Jeanette Francis for The Feed

Revealed by the Prophet Zarathurtra in Iran in 1700 BC, Zoroastrianism is believed to be one of the oldest monotheistic religions.

But dwindling numbers of the faithful have brought a once mighty religion close to being relegated to the history books.

“In about a century's time, they would say this was the last generation of Zoroastrians, -- they're now an extinct breed,” says Australian Zoroastrian Karl Desai.

Mixed marriages are often frowned upon, and partners cannot convert to Zoroastrianism -- they have to be born into the religion.

So the marriage of two Zoroastrians is a rarity and cause for celebration within their community.

The respective parents of one young couple were overjoyed when their children, Rayomand and Binaifer, beat the odds in the name of love and religion.

“The overwhelming feeling is that I have a lot of responsibility being the current generation," Karl Desai told SBS.

"We are hoping that people like Binaifer and Rayomand, when they get married they will pass on a little bit of their religion to their kids as well.”

For now, it's up to couples like Rayomand and Binaifer to carry the torch.