Purpose Driven Life author Rick Warren will be among the religious leaders from around the world taking part in a Vatican conference on marriage and the family this month.

The Colloquium on The Complementarity of Man and Woman will open with an address by Pope Francis. Other faith leaders to share their thoughts on the day include Rabbi Jonathan Sacks and NT Wright.

The conference comes just weeks after Catholic leaders met for the Vatican Synod on the Family, during which the Church came under pressure to change its stance on homosexuality, unmarried couples, and divorcees.

There was a softening of language during the Synod but in the end it concluded with little change to the Catholic Church's historic position.

It is expected that the colloquium will affirm the traditional interpretation of marriage as a union between one man and one woman, and the bedrock of a healthy society.

Around 30 speakers in total from 14 religions will be present to offer their perspectives.

Helen Alvare, a law professor at George Mason University who is working behind the scenes at the conference told the Baptist Press there was a "drive…for new language".

"People fear complementarity means women are second, and their fears are somewhat justified," she said.

"There's a need to educate, to inspire, to show and tell about the beauty of the relationship between men and women."